Green’s Dictionary of Slang

pimple and blotch n.

Scotch (whisky).

1950		P. Hoskins No Hiding Place! 191/2: Pimple. Whisky.
1960		J. Franklyn Dict. of Rhy. Sl.
1971		J. Jones Rhy. Cockney Sl.
1984		Partridge DSUE (8th edn).
1992		R. Puxley Cockney Rabbit.