Sir John Sinclair of Findlater, who died in 1411 at the battle of Harlaw, which ended the Earl of Ross’ rebellion, is probably the builder of Findlater Castle. The castle is clearly modelled on Roslyn, which was the principal stronghold of the Sinclair family. Thus Findlater Castle would date from the end of the fourteenth century, being built after Roslyn.
Note by Knut Ingebrigt Langballe: Nothing further on his wife on Stirnet or RootsWeb 18/10/2010.