This is where it gets interesting and why its been difficult finding info.
My blood relative Neil Thomson was having an affair with her around 1860. They had an illegitimate child Elizabeth - registered as Elizabeth McQuilter (my great, great, great Grandmother).
Mary had further children with the surname McQuilter so I only assume (and because of the affair) she was married to a Mr?? McQuilter.
Neil Married someone else in March 1862. Soon after this marriage, Mary turns up at Neil and his wife's residence and presents them with Elizabeth. Neil and wife raise her as there own and she takes Thomson as her surname.
That's all I know so far.
Know were I can get any more info? (preferably without having to pay for it). Links?
Regards
Craig