muso_bob,
Copy certificates obtained from GRO will be copy of a copy of a copy. Certs from the appropriate Register Office will be copy ( handwritten or typed )of original entry in register. So the signatures of the "participants" are copies not facsimiles.
But some copy certs (typically Marriage Certs) from some Register Offices
( Sunderland, those in Co Durham, etc ), are facsimiles of the original register, and so show true signatures.
Michael