I'm still very puzzled by this one.
Surely the "second marriage" in 1945 must be the bigamous one and he hadn't been a bigamist until this point. So he can't have been imprisoned before 1945. How was it found out

I strongly suspected name changes all round but fathers name, if correct, seems to belie that.
Nothing adds up.
Where is the John George Markinson listed - as a witness on the marriage? Who was the other witness?
Am determined to get somewhere with this one!