Have searched around this evening Brad & cannot find a birth for John or marriage for parents. I did find the following on the GRO birth indexes -
William STANFORD, Sep qtr, 1851, Bicester, volume 16, pg 68
Mary STANFORD, Sep qtr, 1853, Bicester, volume 3a, pg 491
James STANFORD, Jun qtr, 1858, Bicester, volume 3a, pg 524
If you think any of these are yours then if you send for one of their birth certs it will give their mother's maiden name which will probably make it easier to spot George & Ann's marriage.
Regards
Sally