Hi Mags,
From the birth records of your mother and her brothers, this man did not always use a middle name of Peter.
He DID exist as he was present at one of the birth registrations.
The name on his 1965 marriage says Thomas Peter and his parents were called Joseph Edgar (Saddler) and Bridget Tobin.
I didn't look for a birth when I was at the GRO but I have since done a search on SP and think I can see it.
I don't want to post his wife's name here as there is a slim chance that she is still living.
She signed his 2003 DC, and named him simply as Thomas Edgar
Thomas died in Johnstone 17 Apr 2003, and his DC provides the same parent names ( Joseph and Bridget)
However there is a 1917 marriage in Paisley for JOHN Edgar and Bridget Tobin and a corresponding birth for a Thomas Edgar b 1919 in Johnstone.
I still don't have a clue if this man could be your grandfather, but there are similarities.
EDIT:
I am simply putting names together Mags but you should see where I'm coming from with this one...
There is a family in Linwood Renfrewshire at 1901 called Tobin .
Father is called Thomas, mother Bridget with daughters called Bridget and ROSE Ann
I think daughter Bridget could be Thomas's mother and I can see that Rose Ann emigrated to the US in 1928
