Thanks for the answers, Andy. Although I'm still not sure about the correct height of the rudder. The dielectric fin top panel only goes as far back as the rudder hinge line. The horisontal dark line behind this, level with the lower edge of the dieletric panel and that looks like the top of the rudder (if it does not continue to the top of the fin) is actually an unpainted dieletric stripe according to the official maintenace drawings found in the Areofax book. Furthermore Vickers' general drawings, although scetchy, of both the Mk.1 and Mk.2 clearly show the rudder to be of the same height as the fin. Also a cutaway drawing from the RAF manuals, of the fin and fixed tailplane structure shows the rudder hinge line all the way to the top of the fin with no fixed fin area above the rudder.
Several years ago I saw and took a few pictures of XD818 while it was still at Hendon. Naturally I never looked for this particular detail at that time, and none of my photos shows this area. And in 2006 when visiting Cosford, in conection with Nationals at Telford, the new Cold War section of the museum, where XD818 has been moved, had not yet opened at the time. (But I succeeded in taking a load of photos of the TSR.2, including both cockpits! ) Conclusion; still undecided about that rudder...
Guess I will have to concentrate on other areas of this bl...y kit for the time beeing. There is still a lot to do for a masochist! I will borrow the Warpaint volume on the Valiant from a friend to check the remaining accuracy issues and decide what to fix and what to ignore. Or maybe I'll take a break from modelling and watch the forthcomming olympics instead.