There are a few JELLYMAN families at Bloxham which looks more likely. Will see if I can find a suitable Ann ...
Modified to add:
The only Ann JELLYMAN I can see around this time is "Born April the 25th, baptised May 26, Ann daughter of John Jellyman and Sarah his wife" in 1779 at Adderbury. If this is the right Ann she was only 16 when married, a possibility, but I'm not sure yet.
Do you know when she died?