Roy
I found this post whilst researching my family. My grandfather was Henry (Harry) Crowcroft and he married Edith Sophia Willett in Rotherham on 3 Nov 1902. I believe they had three children, Harry (b 1904 d 1989), Muriel (b 1906 d 1906) and another who I could not trace. I believe the third child may be your mother. If so I guess we would be half cousins.
I do not know whether you found out if your grandmother had divorced before remarrying, but Henry remarried in Aug 1942 in Sunderland and my line descends from this second marriage. Henry gave his status as widower. If your grandmother died before this date it would suggest that they did not divorce.
For your information Henry died in Sunderland in 1954.
I would be interested to learn your mother's forenames and place of birth and the fate of Edith, who disappears from the records in the 1910's

Steve