Hi Tessa,
Sorry, I can't help you with your quest, but I came across the same thing with my mothers uncle.
Ben Thomas was born in Marylebone 1897. His father was from Headington, Oxford and his mother born in London. It is believed they may have moved to Oxford for a short time after 1901, before moving to Birmingham, where they settled.
Ben Thomas joined the Oxford and Bucks Light Infantry as well. Sadly he died at the Somme, 16th August 1916, aged 19 years.
I was confused at first, why didn't he join a London based regiment or a Birmingham based one. Perhaps he may have developed strong links with Oxford during his stay or because that was where his father was raised, I'll never know.
Best wishes
Pipkim