Hi Mark, you may already have the information you require, given your post was back in 2007, but just in case you don't.....
I note that The Alfred Culverwell and Sayers marriage occurred in 1915. The index entry shows that the groom was listed as Alfred H Culverwell. Going back to the 1901 census, I note TWO Alfred Culverwells living in Bridgwater Somerset, both of similar ages. HOWEVER whilst the older Alfred (aged) 15 is a polisher at a cabinet makers, the other appears to be your man, as he is an Alfred H Culverwell 13 who is living at the Beaufort Arms Hotel with his parents and siblings.
William J CULVERWELL Head 46 Licensed Victualler (publican) Born Bridgwater Somerset Louisa Culverwell Wife 38 Bn Monmothshire, Blackwood Mabel L Culverwell Dau 18 Bn Glamorgan, Cardiff William J Culverwell Son 16 Bn Glamorgan, Cardiff ALFRED H CULVERWELL Son 13 Bn GLAMORGAN, CARDIFF Elizabeth M Culverwell Dau 12 Bn Glamorgan, Cardiff Rosie (?) M Culverwell Dau 10 Bn Bridgwater, Somerset Elizabeth Perkins Neice5 Bn Monmonthshire, Blackwood.
So it appears that your man was born in Wales, where his mother was born and apparently his father moved to for 10 years prior to moving back to Bridgwater.
GRO BDM shows that William James Culverwell m Louisa PARKER 1882 Spt Cardiff
As one would expect, since he married in 1882, William was lioving in Wales at Blackwood, at the times of the 1881 census where he was living in the large household of Richard and Margaret NORRIS (a grocer and draper ? Your William is listed as a Baker.
Ten years earlier your Willaim James is found as an 8 year old living in Bridgwater Somerset with his parents, James and Elizabeth Culverwell. He has numerous siblings. His father James is a Baker and graocer bn Ashbrittle Somerset. His mother Elizabeth was also born in Somerset, in the parish of Edington.
GRO Marriage indexes indicate that James Culverwell married Elizabeth BARLEY in 1851 (Dec quarter) in Bridgwater, Somerset.
Due to time constraints I will have to finish this post off at a later date.