Keil Kraft 23" Pixie

I cannot see a way of fixing it without pretty much completely rebuilding it, which I am not prepared to do!. I might just put it down to experience and move on.
Many thanks for all your help I really appreciated it.

You already have the plan, so invest in some new wood, cut and save all the formers, and make a new fuselage - keeping it straight this time!

I agree, it'll only take a few lengths of 1/8 or 1/16...

Here's a question, what glue did you use. Today most of us use Aliphatic glue but if you used Balsa glue or Cyano you can soften the glue joints and disassemble the fuselage aft of the wing trailing edge. then pull it straight and reglue. You're going to have extra length on one side which you can cut off.

PVA will come unstuck after a good soak, too!

Thanks for the advice, I will think on it.