Hi Andy,
Unfortunately it's looking likely Charles died before the 1841 census.

I've found his wife Janet staying in Dunbar.
Address: Castle Street, Dunbar
Janet Black, f, 65, - b. Haddingtonshire
Charles ", m, 35, ag lab
Alexander ", m, 30, rabbit catcher
Janet was buried 23rd August 1846 at Dunbar, described as the widow of Charles. There's a possible burial for Charles, "labourer", on the 11th May 1823 also at Dunbar.
Have you looked at the original marriage entry for Charles and Janet on SP? It might reveal what parish Charles was from.
hume24
PS. I do have a Charles Black right time, same area, but I'm not sure if this is the same person. I'll have a check with what I've collected.