So .... there is a Doreen born 1931 whose mum is Mary Blanch Clark, yes? (how is thatknown?) and Mary Blanch's mum is B. Clerker (how is that known?).... and you are saying that B. Clerker signed Doreen's birth cert??
In what capacity? who is Doreen's mum given as on her cert?
This is all too vague to get anywhere, especially with a name like Clark/Clerk!