First post so quick hello to everyone

Right, I'm trying to trace my Grandfather on my father's side, and relations back from him.
His particulars are as follows.
Name: Gordon Richard MARKINSON
b. 09/12/1900 somewhere in London (no birth certificate records)
d. 26/03/1971 in Leeds, West Yorkshire
Served in WWII in the Green Howards based at Gibraltar Barracks, Claypit Lane in Leeds, West Yorks (no longer standing) - served with Brother Frederick who was shot and killed in France.
Worked as a Platelayer for London and North Eastern Railways (LNER or British Railways), also worked in a foundary at some point.
Married 10/09/1945 in Leeds, West Yorkshire - to Nora Reddington
Nora REDDINGTON b. 1913 Ballina, Co. Mayo, Ireland - d. c1973 Leeds, West Yorkshire
The REDDINGTON family still reside on Ballina and have numerous connected relations we are aware of.
It has come to light over the past 12 months, unbeknownst to the rest of the family, that he was jailed for bigamy sometime on or around 1947, presumably in Leeds, West Yorkshire. My father was born in 1947, but does not recall his father not being around at any point long enough to have served a prison sentence. Can only surmise that it was during my father's birth in 1947 or within the first couple of years of his birth. I presume a sentence of this nature would have been served in Leeds, having being a resident there, and would hazard a guess this would have been HMP Armley Prison.
I have spoken to the West Yorkshire Archives dept today who deal with prison records, and have emailed them this information in hopes of finding a missing link.
There could have been a partial or complete name change from MARKINSON, or possibly derivatives of the name; MARKSON, MARTENSON, PARKINSON etc
I did find one family with the MARKINSON name with around 5 children, all MARKINSON, but for some reason the parents were listed as PARKINSON

Gordon was not amongst the children though, and from a different area.
Gordon allegedly had a sister, Rosemary and a brother Fred. Brother shot and killed whilst serving with Gordon in WWII on French soil, sister (along with Gordon's parents) killed during the Blitz (according to stories my father recalls from Gordon).
Gordon's mother (name unknown) was apparently of French descent. No further details known.
Owing to the fact this information was only found out in the past 12 months, the mystery of his past could possibly have been down to name changes, dates, places etc. A bit of a shot in the dark for me as I'm not that proficient at genealogy to know exactly who or where to research. His marriage to my grandmother Nora, a devout Irish Catholic, would have meant this latest information would have been swept under the carpet, hence why my father's cousin had been sworn to secrecy by his mother, Nora's sister, Margaret. They had moved to Leeds and lived together up until Gordon and Nora met and Married.
According to my father, Gordon never really spoke much of his parents or past, so not much is known. The above information is as concise as I can be based on what I know. It would also be useful to be able to link any leads from Gordon's bigamist marriage.
Any leads, links or information that could open up any new avenues to research would be fantastic, and I thank anyone in advance of anything they can do to assist.
