Have you looked at the 1867 Forglen birth entry?Malky
Have you found him in pre 1901 censuses?
Try tracking him back through earlier censuses and looking at where siblings were born. It may be that he spent his early years in Banff and so thought he was born there, but was actually born elsewhere. I managed to track down a baptism for an ancestor who had given wrong birth location on a census by tracing his brother and figuring out the real birth location.
Any "Williams" as witnesses in the marriage cert' ?Malky
Have you looked at the 1939 records?Malky