The first thing I would do is put a request on the Rutland look-up request board. Include a link to this posting for reference so people don't duplicate the look-ups/information already in this post and waste their time.
Based on the idea that Sarah was living in North Luffenham with her husband George Gibson when he died (for no other reason than you have to start somewhere) - ask if anyone has access to transcribed, easily searchable burial records for the years between their marriage and her remarriage to John Clarke and perhaps a few years beyond. If the burial of George is there then it makes Sarah Bains a stronger possibility, if it is found later than the date of her re-marriage then it pretty much rules out Bains as Sarah's maiden name. But also, if there is a burial for another man named Gibson then that would give another line of enquiry to work on.
It is also possible that they were living in Ridlington which is now in Leicestershire so if Rutland doesn't give you any answers you may have to go to the Leics board also, but always remeber to include links to previous relevent posts so peopl trying to help don't get frustrated when they find out you already know things they have just spent time looking for.
