Green’s Dictionary of Slang

one who preaches socialism but espouses a capitalist lifestyle.

1948		Truth (London) 30 July 104/1: [T]he ‘Bollinger Bolshevik,’ is probably quite happy about the ‘ca-canny’ attitude which is worrying Mr. Morrison so much.
1958		Coventry Eve. Teleg. 12 Nov. 1/3: ‘It took me back to the old days when Mr. Aneurin Bevan was affectionately known as “the Bollinger Bolshevik”’.
1979		Sun. Mirror 23 Dec. 11/4: I wish some of our Bollinger Boolshevils would examine this frontier.
1986		R.G. Barrett Godson 53: Bollinger Bolshie and airwaves bore Adam Pratt accosted him for an interview.
2002		Guardian 10 Mar. 🌐 Is Ken Follett a champagne socialist? As a long-term Bolly drinker, he says he quite likes the term Bollinger Bolshevik, coined by fellow writer John Mortimer, but would prefer to invent something of his own.