E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Black Watch.
Companies employed to watch the Islands of Scotland. They dressed in a black or dark tartan (1725). Subsequently they were enrolled into the 42nd regiment, under the Earl of Crawford, in 1737. Their tartan is still called The Black Watch Tartan. The regiment is now called The Royal Highlanders.