Urchin on Family Tree Circles

I have been researching the surname Mainstone for nearly thirty years.

My family go back through my mother Doris Grace Rogers and father Albert William Mainstone, they brought us to live in Cornwall way back in the early seventies. My father was born just outside Bristol (we think) and his mother was born in Mayshill in Gloucestershire, her family (the Mainstone's) came from Iron Acton, there were a lot living their through the Census years. Grandmother's mother was Harriett Hook her family came from the Yate area of Gloucestershire. Grandmother's father was Alfred Mainstone, his parents were Isaac Mainstone and Sarah Webley. Harriett's parents were John Hook and Sarah Ann Griffiths all of these came from Gloucestershire except for Sarah Ann who came from Minety in Wiltshire/Gloucestershire.

My mother's father came from Bristol, his parents came from Nailsea, my mother's mother came from Reading.The previous generation came from both Ireland (Fuller) and Wales (Evans).

I think I have my father's birth certificate, everything adds up except the father's name. Albert William Morgan, an Electrical Engineer, I have been unable to find this person and suspect the name is a fabrication on my grandmother's part. My father would have been known later as Albert William Mainstone but do not know when this happened, he said he was told his birth certificate had been eaten by mice! I need to re-visit Bristol Archives as I had searched for my father at the school he said he attended but did not search under Morgan.

Is there anyone out there that has come across this sort of thing before and could perhaps suggest where I might go from here?