iang

According to Dinger's Aviation page, Roc floats were in fact Shark floats.

I think they were Blackburn Roc floats.

I've not seen any written evidence for this in Admiralty documents, which I have searched extensively. There is also no mention of this change in the 801 Squadron Diary. Of course, the absence of evidence is not evidence of absence, so If Wojtek Matusiak has written documentation on this I'd like to see it. As for paint supplies, presumably any change in colours would have to have been instigated before Implacable sailed for Ceylon in March 1944 to ensure sufficient paint supply in her locker. I also have a copy of the 1771 Squadron Diary and there is no mention of a change in colour to her Fireflies either (and yet there is detailed evidence on the application of BPF markings and codes). Below is a photo of PR240. It looks like it is in standard Seafire colours to me.

Claudio's assumption that replacement's for losses from the Scharnhorst attack on June 13 would be in standard FAA colours is not a bad one, but the evidence is difficult to disentangle because of matching the photographic evidence to the reasonably complex nature of losses, replacements and transfers. Losses on 13/6 during the Scharnhorst attack were: 6A, 6F, 6G, 6H, 7A, 7F, 7L, 7Q. The replacements for Scharnhorst losses were L2939 (6A), L3015 (6F), L2987 (6G), L3024 (6H), L2927 (7A), L2953 (7F), L3017 (7L), L2874 (7Q). Of these replacements: 6G: L2987 was replaced by L2952 11/40, 6H:L3024 was replaced by L3017 by 10/40, 7F:L2953 was replaced by unknown 8/40, 7L:3017 was transferred to 800 Squadron 9/40. There were also other losses among the Norwegian campaign/Scharnhorst survivors that were made good during Mediterranean operation in the summer of 1940. 6B: (probably) L2954 lost on 24/9/40 6L: L3049 lost 3/2/41, 7B: L2997 lost 23/9/40 7C: L2915 lost 3/7/40, replaced by L2909 8/7/40 (previously 7K) 7H: L2996 replacement from 7/40 (ie from beginning of Mediterranean operations) 7K : L2909, lost 24/9/40, 7M: L2891 lost 3/7/40, 7P: L2897 replacement from 7/40 (ie from beginning of Mediterranean operations) 7R: L2956 lost 6/7/40 (probably replaced by L3017 on 8/7/40 ) On 8/7/40 due to losses, 803 Squadron reduced from 12 to 9 aircraft (Yellow Section 7K, 7L, 7M disbanded). Having clearly datable photographs is key here (or finding a photograph of a Scharnhorst replacement Skua which remained in service) . One the best pieces of photographic evidence for replacements use of sky-blue undersurfaces is 6A. Aircraft ID markings on the leading edge were only carried in the Mediterranean, so this is not Partridge's Scharnhorst 6A:L2995, but Smeeton's 6A:L2939. It seems to me that Skua squadrons on Ark Royal may have favoured sky-blue in the early stages of Mediterranean operations. Photographs taken at the end of 1940/beginning of 1941 do not seem to show any evidence of sky-blue undersurfaces, so I assume that by this stage all remaining 800 Squadron Skuas were in Sky.

Here's the photo. It's from my phone, as my scanner is broken.

Looking at the Admiralty records for Ark Royal's aircraft operations in June, the 6 Walrus were not passengers, but actively deployed on ASW and reconnaissance duties most days until they were disembarked on the 14 June. They were coded 5C, 5F, 5H, 5K, 5L and 5M, though I suspect that only individual aircraft letters were carried. Matching the serials to the codes is not possible from the Admiralty documents I have.

On 7 June Ark Royal embarked 5 Walrus from 701 Squadron from Harstad for return passage and 1 Walrus from Glorious on 8 June. Two of these were ex-HMS Effingham (P5662 and P5663). The others serials were P5656 , P5697, P5707, P5711 (all to Harstad via HMS Glorious on 9 May). I have a photograph of a Walrus on Ark Royal, in high demarcation camouflage, which I had assumed was one of these (I can't read the serial), but looking at it again it does not have a fin flash, so it is before 7 June Harstad embarkation. The Admiralty mandated marking a fin flash and yellow concentric to the fuselage roundel of FAA aircraft on 30 May.

Thanks for taking the time to explain, Jamie.

One of the photos in my album shows 7F from the front. In addition to 7F repeated on the cowl, this photo appears to show the three digits from the FN serial - in this case 254 (partially obscured by the a crew member's elbow). Sturtivant gives FN254 as a Wildcat IV with 898 Squadron on Victorious. The album includes a squadron photo of 898 Squadron, so I'm assuming the compiler was part of that unit. FN254 had a barrier crash on Victorious in August 1943 and, according to Sturtivant, the the pilot was RNZN S/L Duff. Interestingly, the album also includes a close-up photo of a Southern Star motif under the fin White Ensign, which the photo caption attributes to a NZ pilot, so it is possible that FN248:7F was Duff's usual mount (though, of course, there may have been more than one NZ pilot).

I own an original photograph album compiled by an unidentified pilot or FAA ground crew who served on Ark Royal, Victorious and Implacable, that contains quite a few "Robin" Martlet photos of varying quality. I was planning to use them for a follow-on FAA Camouflage & Markings volume eventually, so am not keen on posting high resolution copies. I need to scan most of them, but here's a nice photo of 6G: I can't read the serial unfortunately, but it looks like a Martlet IV in USN camouflage to me.

V4690 was written-off by Blackburn in September 1941, and not included in the 1,699 total

Only two of them, and of these one was definitely Fairey built.

I still have a copy of the text of the Aeromilitaria article. This may not have been the final version that was printed, but it is pretty close, For PRO references read TNA: Blackburn Built Swordfish, 1940-44. Fairey Aviation produced a total of 692 Swordfish Mk I between the end of 1935 and the beginning of 1940, before production was transferred to the Blackburn Aircraft Co. Ltd. Blackburn built 1,699 Swordfish (of various types), or ‘Blackfish’ as they were colloquially known, between November 1940 and August 1944. This article is based upon an examination of the surviving Fairey and Blackburn records held at the Public Records Office. Information that survives in the Ministry of Aircraft Production file relating to the Blackburn Aircraft Co. Ltd provides an unequivocal answer to the question of when and why the Swordfish Mk II came into existence. [1] It also provides details of the number of each mark of Swordfish produced that are at variance with figures given in secondary accounts. From the Air Ministry and Admiralty records, it is also possible to draw tentative conclusions about the number of Swordfish equipped with the more powerful Pegasus 30 engine and to the nature of modifications carried out to Swordfish lower main planes to enable them to operate rocket projectiles. The move to Blackburn In September 1938, it was expected that the entire Fairey Swordfish programme of 492 aircraft would be complete by March 1940, at which point Fairey’s would switch production to the new Albacore. According to the official history, the Albacore was ‘greatly delayed’ because of the ‘tardy progress of its engine (the Taurus)’.[2] Because of these delays, in September 1938, the Admiralty accepted an additional 200 Swordfish in place of the equivalent number of Albacores. Fairey’s contract for Swordfish production was increased accordingly. The Admiralty agreed to accept further 100 Swordfish as a stopgap in November 1938, but Fairey never built these Swordfish, however. In an effort to expiate the production of Albacores by Fairey the Air Ministry took the decision in September 1939 to move Swordfish production from Fairey to Blackburn under the Air Ministry extension scheme. The original intention of the Ministry of Aircraft Production was for Blackburn Aircraft Company to act as assemblers at their Sherburn-in-Elmet site for component parts sub-contracted to other firms in the Leeds area. This reorganisation of aircraft production was expensive. The Sherburn site required an initial capital expenditure of £227,000 for the construction of assembly shops and railway sidings. Blackburn (Leeds) was to produce all drawn or rolled form sections and spars for the main planes. Appleyards were to produce main planes and slats and Hudswell Clarke and Co Ltd. the fin, rudder, tail plane, elevators and ailerons. Thomas Green and Sons Ltd were to produce the undercarriage and tail wheel units and London and North Eastern Railway Co Ltd (York) the fuselage. In all, about 120 firms were sub-contracted to produce parts for Blackburn’s Swordfish. These were completely new sub-contractors for the production of the Swordfish. Fairey’s sub-contractors were to be fully engaged on Albacore production. Fairey retained most of the original Swordfish jigs because Fairey were initially required to maintain the production of spare parts, but it was stipulated that Blackburn produced Swordfish were to be fully compatible with Fairey produced aircraft with respect to the manufacture and assembly of all component parts. The Air Ministry Directorate of Technical Development wrote to Blackburn with a detailed specification for the original contract on 21/3/40. Blackburn was instructed to construct the aircraft in ‘strict accordance’ with the Swordfish specification of 15/7/39. The Ministry of Aircraft Production carefully supervised the move to Blackburn. An Aeroplane Production Officer was appointed by the Ministry of Aircraft Production to act as overseer for Blackburn Swordfish production. In June 1940, the Ministry was sufficiently nervous of the capability of London and North Eastern Railway Co. Ltd to deliver fuselages to the production timetable that they instructed Blackburn to produce them instead. This new requirement for Blackburn (Leeds) to produce the fuselage delayed the production schedule. The first Blackburn Swordfish was completed in November 1940, one year after the switch to Blackburn was finalised. Blackburn’s also protested at the shortage of light alloy steel stampings in the spring of 1940 and this was subsequently accepted by the Ministry of Aircraft Production as one of the reasons for delay. Efficacy in the speed of production of complete airframes was undoubtedly also hindered initially by the large quantity of spares required as part of the original contract with Blackburn’s. Indeed, in order to expiate production, a temporary reduction in the stock of spares was sanctioned in January 1940. There is also a suggestion in the extant MAP internal memoranda that delay was exacerbated by a lack of full co-operation between the parent and daughter companies.[3] In an interview with Prof. Postan, in June 1943, the then CNR (Commodore Slattery)[4], contrasted the lamentable war production performance of Fairey’s with Blackburn’s, which ‘always did better.’[5] Indeed, Blackburn production performance, which peaked at about 55 Swordfish per month plus 40% spares, was regarded as ‘a remarkable example of how capacity [could] be organised’.[6] Contracts. The first Blackburn contract was for 300 Swordfish under B31192/39/C20 (b). These Swordfish carried serials V4288 to V4337, V4360 to V4399, V4411 to V4455, V4481 to V4525, V4551 to V4600, V4621 to V4655 and V4685 to V4719. In February 1940, this contract was increased to 400 aircraft as the Admiralty accepted a further 100 Blackburn Swordfish in lieu of Fairey Albacores. These carried serials in the ranges W5836 to W5865, W5886 to W5925 and W5966 to W5995. The 400th Blackburn Swordfish (W5985) was delivered in November 1941, exactly one year after the first aircraft. The original contact was further extended in April 1941 to 500 aircraft, with serials in the ranges DK679 to DK719 and DK743 to DK792. It was envisaged that the total production programme would be completed in April 1942, after which it was planned that Blackburn would produce the Sea Otter. In November 1941, however, the Ministry of Aircraft Production further revised contract B31192/39/C20 (b) and ordered an additional 400 aircraft, with serials in the range HS154 to HS196, HS208 to HS231, HS254 to HS299, HS312 to HS346, HS361 to HS410, HS424 to HS471, HS484 to HS519, HS533 to HS561, HS579 to HS625 and HS637 to HS678. Hitherto, the beginning of the HSxxxx range Swordfish has often been regarded as the beginning of the Swordfish Mark II, but this is not the case, as we shall shortly see. Plans for Sea Otter production by Blackburn were shelved (and subsequently transferred to Saunders Roe). It was realised these inter-manufacturer changes in aircraft production would cause some short-term disruption to production. In the case of the Swordfish, it was understood that Blackburn would not be able to continue production smoothly and there would be a break in production in May 1942. Because the Admiralty were so short of Swordfish for anti-submarine work in the Atlantic, a further 250 Swordfish were ordered in March 1942 (with serials in the range LS151 to LS193, LS214 to LS248, LS261 to LS299, LS315 to LS358, LS362 to LS403 and LS415 to LS461), another 350 in May 1942 (with serials in the range NE858 to NE906, NE920 to NE957, NE970 to NE999, NF113 to NF161, NF157 to NF217, NF230 to NF274, NF288 to NF347 and NF369 to NF414) and an additional 400 in March 1943, of which the last 200 were cancelled. Those produced had serials in the range NR857 to NR898, NR913 to NR958, NR970 to NR999, NS112 to NS156, NS168 to NS204 (the 200 cancelled Swordfish were to have had discontinuous serials in the range NS205 to NS484). In addition, a further 400 Swordfish were ordered in October 1943 (with discontinuous serials in the range RL435 to RL333) and subsequently cancelled in February 1944 Pegasus Engines. The contracts for the first 500 Blackburn Swordfish refer to Pegasus IIIM.3 machines (Pegasus 3). The subsequent contract for an additional 400 aircraft placed in November 1941 (with serials in the range HSxxxx) specifies the more powerful Swordfish Pegasus XXX (Pegasus 30). This is the first mention of the new engine in any Air Ministry contract. Thereafter, it is used consistently in all contracts. In fact, despite the contract specification, possibly as few as 120 of the first 500 Blackburn built Swordfish were equipped with the Pegasus III engine, all the rest were equipped with the Pegasus XXX. There are several additional sources of information which suggest this interpretation: the notes and annotations pertaining to Bristol engines in a file relating to engine modifications for naval types, the contents of a Confidential Admiralty Fleet Order for July 1941 and published photographs. Taking the published photographs first, there are surprisingly few published photographs available of Swordfish in the Blackburn production blocks with serial Vxxxx or Wxxxx, taken from the starboard side (with the enlarged oil cooler visible) and that also have the serial number visible. There are photographs of the following aircraft: V4387 (Pegasus III), V4388 (Pegasus III), V4417 (Pegasus III), V4438 (Pegasus 30), V4517 (Pegasus 30), V4631 (Pegasus 30), V4638 (Pegasus 30), V4689 (Pegasus 30), V4719 (Pegasus 30), W5848 (Pegasus 30) and W5889 (Pegasus 30). In addition, there are other Wxxxx (Pegasus 30) aircraft where the exact serial is not clear, but there appear to be no Wxxxx fitted with the earlier engine. This is also true of published photographs of DKxxx serial Swordfish. It seems extremely unlikely that maintenance departments would have upgraded all of these aircraft. One check as to how likely this is, would be is to find photographic evidence of Fairey built Swordfish retrofitted with later Pegasus 30 engines. These seem to be non-existent, despite the fact that from fatality records, it is known that some Fairey produced Mk I Swordfish were upgraded with the more powerful engine (for example, K5953, P4017 and K8444 are noted as having the later engine fitted).[7] The second piece of evidence is data relating to the modification schedule for Bristol engines. There is a file entry for Swordfish engine modification 317 that is described as a ‘change in nomenclature of engine to Pegasus XXX’. There is also an annotation to this, which reads ‘Blackburn’s responsibility - c.280 engines’. Unfortunately, this note is not dated, but the last item on file is dated 26/11/41.[8] The third source is Confidential Admiralty Fleet Order 1549 of 31/7/41. This advises of the change in engine type and outlines changes in the maintenance specification for the later Pegasus XXX engine.[9] In terms of the delivery of Blackburn Swordfish to units, according to the information in Sturtivant’s Swordfish Story (1993), Vxxxx serial aircraft in the range V4438 to V4505 were first delivered in June 1941, but there would then have been some delay in delivering these aircraft to front line units. What should we conclude from this? After the end of July 1941 (but probably a little before), all Blackburn built Swordfish Mark I were fitted with Pegasus XXX engines. As to the timing of the switch, the fact that the Bristol engine notes on engine modifications to Swordfish are undated is a problem. If these notes on modification were written prior to April 1941, when the DKxxx serial Swordfish were ordered, it may be that as few as 120 Swordfish were equipped with the earlier engine. If the notes post date the DKxxx contract, maybe as many as 220 Swordfish were equipped with the Pegasus III. We will probably never know the exact number, and both these estimates assume that the 280 engines to be modified do not include spares. If this we take the lower estimate of 120 Pegasus III aircraft, it would imply that all Vxxxx serial Swordfish up to about V4440 were Pegasus III. This would roughly fit with the photographic evidence and the timing of CAFO 1549 cited above, as V4440 was delivered in June 1941. The last Swordfish Mk I Pegasus III serial I have been able to confirm is V4417, which was delivered in May 1941.[10] V4438 would appear to be one of the first examples produced of a Blackburn Swordfish Mk I Pegasus 30. It is probable, however, that even if this estimate is broadly correct, Swordfish with serials in the V4411 to V4455 block could have been fitted with either Pegasus III or Pegasus 30 engines as the change in engine appears likely to have occurred on the production line in May or June 1941. Swordfish Mark II There is a brief note in the file headed ‘Nomenclature of Aircraft Swordfish Mk II’, dated 29/5/43, which simply states “The designation Swordfish Mark II has been allotted for Swordfish aircraft modified for the installation of R.P. The Swordfish Mark II is on the secret list.” The Swordfish Mark II was a mark designation change in relation to an operational requirement for rocket projectile equipped submarine hunters in the Battle of the Atlantic in the spring of 1943. This designation is confirmed by a later Confidential Admiralty Fleet order, CAFO 173 of 27/1/1944. [11] This sets out the particulars of the different marks as follows: Mark I The original type, fitted with ASV Mark IIN, front gun, facilities for high-level bombing and F.24 camera. Either internal or external overload fuel tank could be carried. Mark II As Mark I, but fitted with R.P. installation. No provision for front gun, high level bombing or F.24 camera in later production aircraft. A number were fitted with a special version of ASV Mark XI that permitted a crew of three to be carried. Referred to as Mark II ASV Mark XI. Mark III As Mark II, but with accommodation for two crew only. ASV Mark XI with equipment in rear cockpit. RATO gear installed. Internal fuel tank could not be carried, and external tank only if ASV removed. Mark IV Mark I type modified for training duties in Canada in winter. The main modifications included a Perspex hood, windscreen and propeller de-icing. No front gun, high-level bombing facilities or F.24 camera. Only a few of this type were produced. The modifications for the Mark II are described in a separate letter from the Aircraft Maintenance and Repair Department to the Director of Aircraft Production, dated 14/3/43. Two Swordfish (HS 544 and HS 545) were modified by Fairey (Reddish) in April 1943. There were three modifications carried out: Modification 414 (parts A and covered the rocket projectile installation, moveable adaptor frame, modification to the blast plate to fit the adaptor frame and the installation of a master selector switch; Modification 376 specified a requirement for 24 volt electrics and Modification 431 was a sight for the rocket projectiles. The first installation trials for rocket projectile equipped Swordfish had been carried out between 8/10/42 and 8/1/43 at the Aircraft and Armament Experimental Establishment, Boscombe Down. These tests were carried out using Blackburn built Swordfish DK747. The initial test firing of eight 60lb rocket projectiles involved DK747, stationary, and on trestles. Flight tests were carried out on 17/12/42 and were considered successful, but a triple bead foresight was recommended for service use.[12] On the 23 May 1943, a Swordfish of 819 Squadron from H.M.S. Archer sank U-752 using rocket projectiles. H.M.S. Archer sailed on the 19/5/43, and its nine 819 Swordfish would have been embarked shortly after, so it is clear that the highest priority was accorded Mark II production once the modifications had been installed by Fairey Aviation in April 1943. Even so, only 5 additional sets were produced in May. The weapon was brought into volume production in just 14 weeks by ‘turning somersaults’ according to one Ministry official. According to figures provided by the RTO at the Sherburn site, 1,699 Swordfish were produced by Blackburn.[13] Of these, 834 were Mark I, 545 Mark II and 320 Mark III. The number of Mark IV is not recorded in the Blackburn records, though we know from other sources that the numbers were quite small. It is unlikely that the 545 Mark II Swordfish would have been produced sequentially at first. According to Ministry estimates, sufficient Modification 414 sets were only available for 50% of Blackburn’s production in June 1943. It seems likely, therefore, that the Mark I/II break is somewhere in the serial block HS579 to HS625, as both were likely to be found on the production line side by side for a short while.[14] ‘Strengthened’ Lower Main plane. There is only one reference to a ‘new wing’ in the Blackburn file. On the 16/4/1940, there is a letter from the Air Council Committee on Supply (172nd meeting), which refers to the extension of the contract from 400 to 500 aircraft (in the DKxxx serial block). These were to be produced with the ‘existing type of wing’, but that ‘an option should be obtained to have incorporated in these aircraft before delivery the new type of wing and other modifications.’ It seems reasonable to assume that this refers to the partial, non-structural, metal skinning of the under surface of the lower wing and that this change just pre-dates the introduction of the Mark II. It is clear, however, from restoration work on Swordfish carried out by BAe that there are no structural differences between the Mark I and II lower wing.[15] It is likely, however, that the spars were subject to tempering treatment in order to strengthen Blackburn built Swordfish main planes, probably from early 1943 onwards. In the summer of 1942, there were several structural failures involving Blackburn built Swordfish. One machine, V4646, crashed on land and parts of the airframe were extensively analysed by the Royal Aircraft Establishment in November 1942.[16] The structural strength of the main spars was compared with those built by Fairey and the parent firm's spars were found to have a tensile proof stress 11% greater than the failed Blackburn spar. Moreover, new Blackburn spars were found to have tensile proof stress values significantly below the design specification. Although there is no direct evidence in the extant Blackburn production file to suggest that the RAE recommendation for tempering all wing spars was followed, it seems unlikely to have been ignored as the treatment provided a relatively simple means of ensuring Blackburn's spars met the design specification. On a broader canvas, there is some interesting correspondence in the MAP records regarding the divergence between the view of Admiralty and public perception of continued Swordfish production in 1943. As far as the Ministry of Aircraft Production was concerned at least, the public perception of the Swordfish was of a deeply antiquated aircraft, which had had its day. In the interview with Postan, the CNR defended vigorously the performance of the Swordfish, ‘The Swordfish is called a slow and obsolete aircraft, but…for the first three years of the war, it did its job superlatively well.’ The Admiralty clearly regarded the Swordfish II as a crucial weapon in the U-Boat war. The CNR described the Swordfish as ‘the most successful aircraft they now have’ (in June 1943) for the Battle of the Atlantic.[17] The use of rocket projectiles was classified ‘secret’, and, therefore, the success of the Swordfish II was not widely appreciated. In contrast, the spectacular failure of torpedo equipped Swordfish during the ‘Channel Dash’ debacle, in February 1942, was reported and this information asymmetry almost certainly explains the poor perception of the aircraft. The metamorphosis of the Swordfish from a pre-war designed and produced fabric covered TSR/B biplane, which was obsolete in this role prior to hostilities, to a mid-war submarine hunter-killer par-excellence, is an example of how the piecemeal improvement of old types helped maintain the quality of British naval aircraft in the face of the slow (and generally disappointing) development of replacement types during the early and middle phase of the war. The mass-production of Swordfish, and the speed with which transfer to the rocket equipped Mark II was achieved, is also a testimony to the efficiency with which the Blackburn Aircraft Company organised production at their Sherburn plant. [1] PRO file reference AVIA15/237 [2] Postan, MM, Hay, D and Scott, JD Design and Developments of Weapons (HSWW, HMSO 1964) p.134 [3] PRO file reference AVIA46/143 [4] The Chief Naval Representative was a naval officer of Flag rank who represented Admiralty views in the Ministry of Aircraft Production. See Scott, JD and Hughes, R The Administration of War Production (HSWW, HMSO 1955) pp.153-5 [5] PRO file AVIA 46/136, Interview with Commodore Slattery, 25/vi/43 p.12 [6] PRO file AVIA 46/136, Interview with Commodore Slattery, 25/vi/43 p.13 [7] Correspondence with Ray Sturtivant. [8] PRO file reference AVIA15/2866 [9] PRO file reference ADM182/131. CAFO 2131 of 30/10/41 amends the previous order and includes a description of the larger oil cooler (modification 344). [10] The fatality records indicate that V4380 was fitted with the later engine (information provided by Ray Sturtivant in correspondence). V4646 was also so equipped. Accident report, PRO file reference AVIA5/21. [11] PRO file reference ADM182/137. I am grateful to Ray Sturtivant for providing the reference to this file. [12] PRO file reference AVIA18/1022 [13] In addition, V4690 was written-off by Blackburn in September 1941 [14] The fatality records give HS657 as Mark I and HS615 and HS638 as Mark II. Rather oddly, HS439 is also listed as Mark II. Data provided by Ray Sturtivant in correspondence. [15] Information supplied by Paul Fontenoy in correspondence. [16] PRO file reference AVIA6/8107 [17] PRO file AVIA 46/136, Interview with Commodore Slattery, 25/vi/43 p.4 Indeed, Slattery implies that the Admiralty preferred Swordfish to Avengers.

Lee, All of the mark descriptions in FAA 1939-45 for Blackburn Swordfish before MK III are wrong. I thought you had amended this years ago in your digital files? 1anG

Sadly, that is all incorrect. My research is based upon the extant Blackburn production records held at TNA. I've published an article on this in Aeromilitaria (Air Britain), which laid out all of the details concerning marks and the change over to the more powerful Pegasus XXX engine (which Sturtivant also has wrong). This one: Ray commented on the contents and accepted the conclusions before he died.