As it's a brand new one fresh out of the box, the silver maskers, which holds it together, hasn't been painted over yet (unlike the 30-50 year old aircraft to which 'our chaps' are more accustomed).
Hope this helps. :wink:
PS: I'm glad the silly testing phase is now complete also. Is the 'arsing about phase' before or after the final acceptance bit? It's just that the RAF seem to have been taking an awfully long time over this phase with the Typhoon.