Must admit, I didn't look at the other pages (will now), so hadn't seen any with the yellow. If George Unwin's kite is there, with yellow leading edges, then it's definitely wrong ! Apart from the fact that, as already mentioned, the yellow hadn't been introduced in 1940, I've got a DVD with some footage and 'stills', showing George and his Spit - and of course, no yellow!
I find it strange that any artist could make such a fundamental mistake, even if using the same base drawing for all profiles, and even if under the pressure of a deadline ! Had it been a month or so either way, in say 1942, then there might be an excuse, but not in the BoB !!!