I have got the certs now. Thank you for sending

So, in summary, we have the original signatures for Sophia Anderson and John Watson on their son George's 1877 birth cert. However, Sophia's marriage cert (from SP) is a copy from the original so it does not show her signature, simply states 'signed' (written by the clerk).
I thought to look at John Watson's marriage to Ann Andrew that we have been discussing. Drat! That also was a signed copy of the register so no original signature for John Watson showing there. I have also checked the birth cert for first born son to John Watson and Ann Andrew. The birth was registered by father John Watson and he has signed the birth register.
Below are the two signatures. On the left is the signature for George Watson's birth for father John Watson. On the right is the signature for William Andrew Watson's birth in 1897 for father John Watson.
Same signature/John Watson?