Green’s Dictionary of Slang

waterbury watch n.

Scotch whisky.

1914		Eve. Herald 21 July 2/: Rhyming slang is on the increase [...] but I think the limit was reached the other day by a ‘nut’ who demanded of the lady behind the bar [...] ‘A Watebury Watch and a Major Loder’. The Hebe, who was undoubtedly a ‘nutess’ [...] provided him witha Scotch and Soda.
1932		‘P.P.’ Rhy. Sl. 13: Feeling ‘current cakey’ this morning, give us a ‘waterbury watch’ and I’ll have an ‘ocean wave.’.