That should be it! Thanks greatly, Anne.
There were several James Mushets in this family - I was trying to work out whether a marriage to Marion Mitchelson in 1849 was of my ancestor James Wallace Mushet (second marriage) or his son James. It's my ancestor. Thomas is the youngest child of his first marriage, to Helen Garrie in 1822 when he was quite young. James has knocked a couple of years off his age here - he'd be 46 or 47, depending on the date the census was taken.
The name is usually either Mushet or Mushat - SP has it transcribed as Mushat for this census, which I'd picked up with a wildcard search. Andrew, I'm interested in other Mushat/Mushet/Mushots from this census also, particularly the households of the younger James who'd be approx. 22, and brother John aged approx 24 though I don't have a firm birthdate for John. They could be anywhere in the Glasgow or Greenock areas.
And now to write to my possible cousin to say it's looking more likely my James Mushet is also hers - with Marion shown as his wife

. And to try to track James in the 1861 census, where there should also be a younger child born around 1852. James died in 1870.
Jenny