First of all thank you for your quick responses.
Henry married Annie Elizabeth Wraight on 13th April 1918. His father's name is listed as Albert Alfred Simmons and he was listed as a private. Frederick Wraight is Annie's father and he was a farm worker. Their wedding took place in Faversham, Kent which is where Annie was from. The witnesses were Alfred John Parker and Emily J Parker.
I have the same census records and feel that it must be the right family, but I didn't know about George as I think he died at 2 years old. A brother is listed as Albert Alfred and nobody in the family has heard of him either so I don't know if he died in the war or even if he served in WW1.
I don't think that my grandfather originally had the surname of Simmons as we believe that he was born when Florence was in service. (Sorry - don't know where) We believe that the master of the house may have been the actual father and Henry may have been registered under Florence's maiden/previous name, but we have no idea what that was.
On the 1911 census it is stated that the marriage (between Alfred James Simmons and Florence) was 24 years previously. I can't find any record of it.
Thomas Owen was his brother and Owen was his surname. I think he must have been the eldest. I don't know how many times Florence might have been married either or why he has a different surname.
Henry Simmons 2nd Scottish rifles 9772
and Royal Flying Corps G/26977
If you need any more info please let me know. The baptism records are interesting, I hadn't found those. The main areas are Bethnal Green, Poplar, Stepney, St. George in the East, St. Lukes and St. Pancras.
Thank you both so much for offering to help. If I missed any answers let me know!
Julie