Thanks for all those thought and ideas Pennie!
Had an interesting result from the OBI - what a great service this is :-). The man who conducted the search was also kind enough to take another look at the wedding and, indeed it is true that the wedding was by licence. Like you, he also thought this could mean that there was some 'need' to perhaps avoid marriage in their home parish(es). It is also worth noting that Charles is described as being from Oxford and Sarah from Adderbury...whilst this may have been so, I'm reasonably (ha! I perhaps shouldn't be after the Chipping Norton Sarah incident) happy that this is the correct couple, and that possibly their home parishes have been swapped along the way....?
I seem to have a note from a while back that there were no suitable marriages between a Charles Walter and any other suitable Sarah in Northants, another reason to lead me back to this marriage.
Whith regard to her age - lets say she was born in 1778, making her only 14 at the time of marriage. A good reason to avoid the 'home' parish maybe? I do have one other very young marriage like this, on one of my Mum's lines. In that case, the bride was most definitely 14, the groom 28!! Took me some time to sure I had the right couple there, I can tell you!
The OBI does not record any other suitable Sarahs being baptised in the necessary time frame. Always remembering there are some parishes missing at this time. Northants would be interesting to look at, being so close, but knowing where to start searching for a baptism is something of a 'needle in a haystack.' I've also noticed there are several GUY families on the OXF/Gloucs border...all adding to the fun LOL!
My next avenue of pursuit is to contact the record office to see if the wedding licence notes are available, and if so, whether they can tell us any more....
Thanks again for have a ponder over this puzzler :-)
Jenna