If you look on the familysearch IGI site, theres a marriage for George Maisey and Martha Legg, no date, just 1833, but theres also a message -
"Record extracted from Oxfordshire Marriage Transcripts 1538 - 1837. The indexes do not contain any further information, but the printout may contain names of people who may be brothers, sisters, other relatives......!
So, you could order the film, I think, (never done it myself) to look for other Maiseys/Leggs, which may give further clues.
Alternatively click on the "batch number" on the page showing George and Martha's marriage, then type in "Maisey" or "Legg" in the surname box, and up comes another marriage right at the bottom of the page -
John Maisey and Letitia Legg 1830 Fullbrook
possibly 2 brothers marrying 2 sisters? or cousins? Finding them on the census may give clues to their parents.....