Thank you to everyone who has replied - I didn't know you would be so quick! Yes, I have tried all the death certificates from Marlborough, Birmingham, Hove, etc. No luck. Yes, they were living in Goring in 1911. Don't know when he left his wife and 3 kids (my other maternal grandfather did the same, leaving wife and 6 kids!).
He left WW1 as a lieutenant, so not sure if he joined another regiment overseas.
His birthday 29/04/1875 at Maidstone. I think that Maidstone was also a military barracks also. Have looked at the 1939 Register (thanks) but no luck there either.