McCoy [M19th] The source of the real McCoy is far from clear. The trouble is that McCoy is a relatively common surname and so there are numerous candidates for the post of the original McCoy. The earliest example of the phrase, dating from 1856, is Scottish, uses the form McKay, and describes a brand of whisky: ‘a drappie [drop] o’ the real McKay’. The distillers G. Mackay and Co. apparently adopted ‘the Real Mackay’ as an advertising slogan in 1870, and this was the form familiar to novelist Robert Louis Stevenson, who used it to mean ‘the genuine article’ in a letter in 1883. It seems clear that the expression was well established as the real McKay by the end of the 19th century, but in the early part of the next century most examples have the McCoy spelling and are American. Possibly the most likely reason for this spelling change is one Norman Selby, also known as Charles ‘Kid’ McCoy. He was an American boxer who became welterweight champion in 1896 after knocking out Tommy Ryan, his sparring partner, to whom he had previously pretended to be ill and unfit. Apparently he often used this trick of feigning illness, only to appear fighting fit on the day itself, prompting commentators to wonder whether this was ‘the real McCoy’.