So where did she marry? English marriage certs dont give place of birth.
Definite info (as far as pos) then is-
Grave says she was called Constance Ada Sayer, and was born March 1892
Marriage cert to Frank Sayers in Essex (oh, that answers my question above!) says she said her dad was Alexander Williams Horse dealer (Hmm may have made that up for marriage, if she was illegit)
Who were witnesses at her marriage - in case they help