I am sure somewhere (maybe on Footstompin') I read that Mari's wedding was a mod song writing winner and the prize was presented by Princess Margaret.Possibly in the 50's and the Mari it was written for or sung it was only a wee lassie at the time.
I remember learning it at school but there again I also learned The Wee magic Stane and Pitenweem Jo at as well as Hugh Roberton songs