Sarah Trevanion

Information given below also in Vivian's "Vistations of Cornwall', which is probably the origin of this repeated error.

Nicholas also married Sarah LITTLETON, daughter of Sir Edward LITTLETON and Unknown, on 29 Oct 1716 in St. Stephens by Saltash, Cornwall. (Sarah LITTLETON died on 27 Sep 1719 551 and was buried on 30 Sep 1719 in St. Germans, Cornwall 551.)

http://www.celtic-casimir.com/webtree/23/47331.htm'

Vivian is confusing Sarah with Sir William Carminowe's first wife, Susannah, who was indeed Sir Edward Littleton's daughter.