I have checked with my cousins in Scotland who have a large file on our Selkirks and our family name of Pryde . Here is their information:
In 1882 two gamekeepers were killed by a couple of poachers on the Roseberry Estate near Gorebridge.One of the poachers was Robert Flockhart Vickers (whose mother-in-law was a Pryde - hence the connection)He was convicted and hanged three months later at Calton Jail in Edinburgh. They traced back his ancestry for a few generations with the following result:
Robert Flockhart Vickers born 1846 in Cockpen, son of William Vickers and Jean Flockhart William Vickers born 4 July 1812 in Skipmuir, son of William Vickers and Helen Selkirk Helen Selkirk born about 1791 in Liberton, daughter of Alexander Selkirk and Margaret Stevenson.
They think this Alexander could have been the son of William Selkirk and Helen Hislop.The names all follow the usual pattern and the clinching factor for them is that there were several members of this family called Ramsay which is rather an unusual Christian name in Scotland.
They don't have the parent's names but William's birth is about 1734, Cockpen and Helen's is about 1738, Cockpen.
As far as they know, they never did establish a connection between our Selkirks and theirs, but bearing in mind the Christian names they think there is every possibility of one.There may be more information later on as one of the cousins is on holiday.Will get back to you if there is.