I spoke with Gordon's brother, Ernest Markerson and he says in addition to what we already know, that the reason Gordon and Phyllis are registered both at the same address at the time of their marriage, is due to Gordon living with (as a lodger), Phyllis' patents. He used to clean their brasses. He also states that Gordon got Phyllis pregnant hence why the first Gordon/Phyllis offspring was so close to the marriage date.
Ernest has also said he had quite an extensive record of the MARKERSON family tree of his cousins, dating back as far as 1854. He is going to let me have this information which may open some clues and hopefully missing links to Gordon's father George.
Ernest is known as 'John' by his family.
Ernest also said he had reservations about his 2 deceased siblings, Phyllis and Reginald as to wether they were his real siblings, so they're could well have been a marriage/family pre Phyllis OAKLEY.
Ernest wife mentioned something about Gordon's father, George, seeing somewhere his occupation being 'Horse Whisperer', and that he was probably from the USA. This may be just an assumption on her part and shouldn't be taken gospel.
I'll update more as and when.