I have an L-Reg Peugeot 405.  The other day, I needed to access the
boot and during the normal process of inserting my key, turning and
pushing the release button, the key stuck in place.  The key is
inserted fully and will not come out.  Nor will it turn left or right.
I can still push the button in, but this doesn't release the catch.

Clearly, the rear seats do not fold down, although I have a small
opening behind the arm rest for very restricted access to the boot.

Has anyone had this problem before?  What do you recommend to fix it?
I have tried WD-40 and releasing the key with a paper clip.  The RAC
has tried to release the key, without success.

Ideally I would like a solution that will not do damage to the lock (I
don't mind damaging the key though as that's easier and cheaper to
replace).  Is there a central control lever that I can use to open the
boot from inside the car?

If I need to damage the lock, how can I do so with minimum impact (and
repair cost?)

Thanks,
Chris