I unpicked the seam on the kestrel, and very very carefully lined the two halves back up, and pinned and basted it, and checked again that the crucial part of the wing matched properly, and sewed the seam… and it still doesn’t quite line up. So that’s it. I’m giving up and accepting the fact that the kestrel is doomed to have a slightly wonky wing. I just can’t face unpicking it again (and anyway the paper pattern is completely falling apart after being sewn and unpicked and sewn again, so each attempt gets harder to keep accurate).
Sorry about the rubbish photo – I took it late last night when I gave up in frustration.