Yes I know what is required ....
I was replying to the guy that stated this ......
"I recently had stamps transferred to a new UK passport at CW, supported by an embassy letter supplied by VFS. Nothing else required"
First up there are other things required as you pointed out.
Also there is now more than one post apart from the OP , stating that for using money in bank method that now CW are requiring bank account details for stamp transfer.
If this is across the board at CW then that's a new requirement.
Something that I certainly did not provide some time ago.