But an 'R' examiner is also an 'R' instructor!
I didn't mean that the authorised signatory must be a Flight Instructor.
You don't surrender a PPL to the CAA, they will, if necessary, re-issue it in the new format with a new number.
My old 1968-era BoT-issued PPL was replaced by a new-style PPL with a new number; that was replaced by a R/BCPL and ultimately an ATPL. I could have chosen to have either the R/BCPL or ATPL re-issued, but not both. The 'lifetime' new-style UK PPL can be revalidated if the ATPL expires and I transfer the relevant ratings to it, but otherwise it is in suspended animation.