I found out, as an adult, that one of my aunts wasn't married to my uncle, but that's as far as it went, although I had overheard other aunts saying about her "Well, of course, she can't have any children". I don't know if that meant she couldn't physically have children, or she couldn't because she wasn't married. I know they wanted to adopt me, but naturally my mum wouldn't give up her first born and only daughter but I did stay with them often and really loved going to their house.
Years later, when my mum's mind was going a little, she suddenly came out with the whole story and told me my uncle's real surname (they had used my aunt's middle name which was her mother's maiden name as their surname) and the fact that he had left a wife and 2 sons and had lived only a few doors from them. I've now traced his wife and sons (only on paper), as well as finding his birth and finding him on 1911 census.
I don't suppose there was ever any option of getting a divorce in the 1930s, or perhaps the wife wouldn't divorce my uncle.
Lizzie