Margaret McMurray (died 1760) appears to have been one of the last native speakers of a Lowland dialect of Scottish Gaelic in the Galloway variety.
[1] In The Scotsman of 18 November 1951 appeared the following letter, which had originally been printed in the Daily Review in 1876: Sir-I send this in corroboration of the fact that Gaelic was to some extent spoken in Ayrshire in the early part of last century.
Cultezron was possessed by several generations of McMurrays, and its name is purely Celtic Cul Tigh Eobhain, (sic) signifying the 'back of Ewan's house'.
D. Murray-Lyon Ayr, October 31, 1876Cultezron (not to be confused with nearby Culzean) is a small farm on the outskirts of the town of Maybole in South Ayrshire.
It appears that Margaret's family had been in possession of it for at least 150 years prior to this, as one 'John McMurray' is in legal records at that time.