« Reply #1 on: Thursday 23 May 19 00:00 BST (UK) »
The marriage of William H and Ruth L was in 1939. However, the mother's surname in the GRO index for William V's birth is "Nathey". FreeBMD shows one other entry for that surname, a marriage in 1866. I suspect a mistranscription into the GRO index.
No wait. This is sensitive info so I will not post it. I will send you a PM.
I would add a "postem" to the birth record at FreeBMD, with an email address where a family member who saw it could reach you.
HILL, HOARE, BOND, SIBLY, Cornwall (Devon); DENNIS, PAGE, WHITBREAD, Essex; BARNARD, CASTLE, PONTON, Wiltshire; SANKEY, HORNE, YOUNG, Kent; COWDELL, Bermondsey; COOPER, SMITH, FALLOWELL, WILLEY, Notts; CAMPION, CARTER, CRADDOCK, KENNY, Northants; LITTLER, CORNER, Leicestershire; RUSHLAND, Lincolnshire; MORRISON, Ireland; COLLINS, ?; ... MONCK?