Here's a line from Salford council's FAQ on cremations:
Is the coffin cremated with the body?
Yes. The Code requires that nothing must he removed from the coffin after it has been received from the chapel and it must be placed into the cremator exactly as received.
I have a friend who took his mothers body in a cardboard box to the crem in
the back of a pick up truck [no lie] thats why he has more money than me.
when I said no lie that is the truth.
collaton
eddie, that is simply not true in the uk. crematoriums are governed by a strict code of conduct and there is a strict ethical code which is always adhered to. there is absolutely no way what you describe could happen.
a coffin for a cremation has to be of a particular material so that it will burn properly. all metal fixtures and fittings are left on and removed afterwards, including metal prostheses.