Found: Obscure book

This is a long shot as I've tried Google and gemini and I can't give them enough information for them to identify what I'm talking about. Many years ago I read a book set in England in modern times. It starts out I think with a pilot who wakes up in a field. He was killed in the war and has somehow woken up years later. It turns out there has been some kind of nuclear war and an effect of the fallout is that people from the past who have died before their time are reappearing, I remember it said in the book that so many were appearing at execution sites like Tyburn that someone had to be permanently stationed there. Many have died in the nuclear war and Richard iii has returned and is reigning again.

Things Unborn. Found it by Googling "Richard III" + "nuclear war" + "novel"

OMG thank you