I may have solved this one but I'd like Rootschatters feedback, there are so many variables. Bear with me please - I give full info so people don't do unneeded searches.
My relative George Thomas Cox was registered in Warwick district in the first quarter of 1889 and baptised 3rd February at St Mary's Warwick. His mother Mary Lewthwaite was from Middlesex, his parents married in Woolwich where his elder sister was born, his father Thomas died in 1890, his mother remarried to James Mackonachie (spelling varies) in 1892 in Greenwich, and in 1901 he is with them in Greenwich as a Mackonachie, though on Ancestry someone has helpfully added a correction that he is a Cox. In 1911 he is in the Army in India (Rifle Brigade) born Salford Warwickshire which might mean Salford Priors but which I think is a mistake for the Saltisford area of Warwick town (His brother Thomas Albert gave his address as Saltford, Warwick when joining up later).
Thomas Albert didn't survive the war, but I know George did because I found an "attestation" for him from the Rifle Brigade dated 1919 which, stupidly, I didn't save and now can't find. And that was the last of I saw of him - no death except in Thanet 1934 which would be a year out in age - except that I saw a George T Cox in Wandsworth on the 1939 married with an Elizabeth E born 1899 and a Daphne G b 1919 presumably a daughter - and this George's biirth date of 7/1/1899 was very close to my George's baptism. However I could find no marriage of a George T to an Elizabeth E in the time period, neither could I find a birth record for Daphne G Cox, so I put the matter aside.
Then I got access to the 1921 census at FindMyPast. I know that requests for this are prohibited, but surely I'm allowed to give a brief outline of what I found? George Thomas Cox 32 and Elizabeth Ellen 22 are boarding in Southend. He's born Salford Warwick, which makes me confident he is my George. He has the same profession as one of those he gave in 1939.
But who is Elizabeth Ellen born Bardfield, Essex? FreeBMD (searching without surname) finds plenty of those born in Essex around 1899, but none found in Braintree district where Great Bardfield is. I next tried Daphne G, missing in 1921, and the best birth record I could find was Daphne Georgina Gilbey, illegitimate, registered Dunmow district in the right quarter.
I trawled for Elizabeth on censuses and found that she may well be Elizabeth Ellen Gilbey born and living in Little Sampford, Essex, a daughter of Charles Gilbey - and this fits a birth record in July quarter 1899 in Saffron Walden district which is where Little Sampford was - and also fits the birth date she gave in 1939 as a Cox. Moreover, by 1921 Charles and family, though given as living in Great Bardfield, were in fact at an address in Little Bardfield, which was in Dunmow district.
So I think this is my George and his never-married partner. Do you agree?
There's a further problem with Daphne Georgina Gilbey, later Cox. I can't find her in 1921 - she's not with either grandmother - and I'm not allowed to ask you to look for her. (Daphne Georgine Rice in Colchester and Daphne Coe in Dunmow are not her.) The 1939 gives her future married names Pound and Moore,but I can find no marriage for her to a Pound as either a Gilbey or a Cox, though I found her 1973 marriage to a Moore as Pound.
More seriously, is she George's daughter? She was born 10/7/1919 exactly 9 months after the Armistice, but I think I've read that it took a long time to get all the soldiers home, and "regulars" like George would not be demobbed. Although he could have been on leave at the right time. He could have just taken up with a young woman with a baby - but why was she given the unusual middle name Georgina?
If anyone's had the patience to read through all of the above, I'd appreciate your thoughts. Thanks, Chris