Hi Anna, thanks for your suggestion, that really helped me out, though not quite in the way you might expect!
I already had a burial record for Thomas, proven to be the right one because the address given agreed with the baptisms of the children. Unfortunatley it gave his age at burial as 46 and he was buried 2 November 1833, giving a birth date of 1787!!! This didn't link closely enough with either of the 1784 or 1793 dates to convince me.
However, in following up your suggestion, I looked at the burial records for Thomas and for his wife, Jane, who was buried 20th June 1836, orphaning the children, who we then find with various families / institutions in the 1841 census. She was aged 41 at burial and so would have been ~ 38 when Thomas died in 1833.
That means that their ages were quite different (8-10 years). I know Jane was born 1794 so that establishes that her husband was the 1784 Thomas, not the 1793. The answer was there in front of me all along, but I never spotted it until you pointed me back to the burial records.
Thanks! Pete Hulme