Hi Duncan
There are two entries on the Wills & Testament section of
www.scotlandspeople.gov.uk for a Thomas than be the one born to James and Margaret (Scott). The detail shows:
Thomas Bennie, 6 June 1853, Warehouseman, thereafter Baker, residing at 296 Duke Street Glasgow - GLASGOW SHERIFF COURT - INVENTORIES - SC36/48/39 3 pages.
Thomas Bennie, 6 June 1853, Warehouseman in Glasgow, Spouse of Mary HORN, son of Margaret SCOTT Or BENNIE - TRUST DISPOSITION AND SETTLEMENT - GLASGOW SHERIFF COURT WILLS - SC36/51/32 3 pages.
Possible marriage in the Old Parish Registers in 1838
https://familysearch.org/pal:/MM9.1.1/XTYB-89SNot much to help further on possible census entries:
1841:
Thomas Bennie 40 Shopman
John Bennie 13
Mary Bennie (mrs) 40 born outside of Lanarkshire
1851:
Thomas Bennie 52 Draper b. Glasgow
Mary Bennie 52 b. Fife - Dunfermline
Address: 18 Little Hamilton St, Glasgow
Not sure if this is the correct Thomas though. With this all being pre 1855 and the start of official registration of BMDs, information will be harder to confirm.
Monica
Added: An advertisement for 1844 for the above Thomas I think!
www.flickr.com/photos/robertpool/5345376725/