I think I'm a bit clearer after some further digging. To summarise:!
1911 census is Mary Yates, her daughter Elsie Jenkins (found them living in Lye, Worcs in 1901 census, Mary then married to Thomas Jenkins), with the son of Leon George (age 6mths) himself named Leon, and Basil Yates, the older Leon's brother. The census has a George Yates at barracks at Carrisbrook, Worcs Reg.
There are two pension record cards. The first for Leon George, has Leon crossed through, gives dependent as Elsie Jenkins - relationship 'unmarried wife with one child'. The second has Leon George, also with Leon crossed through (same reg number as the first card), widow Mary Ann and child Leon, but this states that Mary Ann is ineligible for the pension as she is separated from husband prior to mobilisation. Had Leon senior eloped with his daughter in law do you think?