I'm not sure if I'm looking at the right couple, but in 1851 is this them?
http://search.ancestry.co.uk/iexec?h...c=&pid=4058361
That says Ann is 42 and from Shrivenham.
How do you know Ann's mother's name? I noticed there was an Elizabeth Lambourn living with John and Ann (ann is recorded as 27, so that works out to 1814, but would make her quite young at marriage - not impossibly so), but Elizabeth is 84, so perhaps grandmother rather than mother?