« Reply #3 on: Tuesday 02 October 12 10:39 BST (UK) »
replying on thread as it's better to keep all replies where they can help other researchers. He may be hidden in census entries by a change of name if his mother has remarried. Could you give the census ref for any entries that you have for him, please?
Do you have his marriage cert? Does it give his age and his father's name? If you don't have the cert, it would be a good idea to get it.
I can see a William born Camborne in Monmouthshire on the 1891 census RG12/4370 folio 46 pg 5. Is this the man you are trying to trace? We need details of what you know so that we're sure to look at the same man.

Cornwall: Allen, Bevan, Bosisto, Carnpezzack, Donithorn, Huddy, James, Retallack, Russell, Vincent, Yeoman
Cards: Thomas (Llanbadarn Fawr)
Glam: Bowler, Cram, Galloway, James, Thomas, Watkins
Lincs: Coupland, Cram
Mon: Cram, Gwyn, John, Philpot, Smart, Watkins
Pembs: Edwards (St. Dogmael's)
Yorks: Airey, Bowler, Elliott, Hare, Hewitt, Kellett, Kemp, Stephenson, Tebb