When the Spitfire family was curtailed with the Mk XVIII / XIX, Supermarine's design department, previously absorbed by Spitfire developments, had nothing in train to replace it. Thus the MAP had little compunction in forcing Supermarine into using its production facilities to produce another's design; in this case, Martin Baker's MB5.
Although the Spiteful name was already being considered by Supermarine as a potential laminar flow-winged development of the Spitfire, many saw the name as encapsulating Supermarine's attitude to building another company's design.
The build represents a Spiteful of 91 Sqn, 2ATAF, based at Volkel in early 1945.
Regards
Martin