Thankyou for your suggestion.

As usual I do not include ALL the information in my original posting,
I always forget something!

The toilet cannot be raised, it fits under a window in a specially
designed alcove. Taking it out and replacing it would be a major
operation and would require considerable reconstruction. it is already
on a concrete plinth which raises it about an inch from the concrete
floor into which I assume it is bolted with ragbolts, because only the
nuts show.

I tremble at the thought of removing it!!!

Peter.