Peter, it might be worth calling Keith at BHM.
I did exactly the same thing, leaving a buried stud in the woodwork. I was mortified - on a brand new Morgan too.
I took it to BHM and they repaired it - without a mark. I've no idea how they did it, but it's obviously something they've done many times. Keith is a friendly chap and I'm sure he won't mind telling you how to do it....
