« Reply #6 on: Friday 24 October 08 12:35 BST (UK) »
still can't spot him on the census, it may be a question of waiting for the 1911 to be available.
The only birth reg to fit that birthdate for a David Henry in Glam is
David Henry Griffiths march qtr 1889 Merthyr Tydfil vol 11a pg 542
Born Barry, he would have been registered Cardiff, and Tonypandy would be Pontypridd. Might be worth a shot if no-one else can find him on the census.

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