Thanks for your thoughts Annie, and thanks for the clarification Neale. The address as simply “Glen” came from Ancestry, but freecen’s transcriptions seem to be more accurate.
Auchterarder Fifeshire was the transcription from the 1851 census.

Klouman at reply #2 suggested Elizabeth Anderson at Greyfriars Wynd Glasgow as a possibility in the 1841 census.
This Elizabeth was not born in county, aged 60 b 1781 living with with Robert Anderson, Tailor/Sailor.

Robert is 30 so bc 1812 and vaguely born in “Scotland”and, if the correct family, could be brother to my John. There is also a 9 year old Margaret Anderson.
I think I might have found this Robert in 1851 age 39, a “Trading Sailor”, with wife and family. Robert transcribed as being born in North Queensferry Fifeshire. I’m not convinced that this Robert is related to my John, but if he is, it could be that the family moved to Glasgow after the birth of Robert.
Pure speculation and may be completely wrong.