Green’s Dictionary of Slang

1. (a pint of) bitter.

2002

B. Kirkpatrick Wicked Cockney Rhy. Sl.

2. (also Gary) the anus [= shitter n.¹ (1)].

1997		Roger’s Profanisaurus in Viz 87 Dec. n.p.: Gary Glitter rhym. slang Arse. From Gary Glitter – shitter. See also council gritter.
1998		I. Welsh Filth 301: Getting it up the Gary Glitter.
2001		K. Sampson Outlaws (ms.) 94: There’s a big chunk of chopped tomato right in the middle of her Gary Glitter.
2003		B. Dark Dirty Cockney Rhy. Sl. 59: Ask her if she takes it up the Gary.
2008		J. Niven Kill Your Friends (2009) 65: Two hours later, I’m doing her up the fucking Gary.
2015		N. Cummins Tales of the Honey Badger [ebook] I decided to pull up stumps on the old Gary Glitter to initiate movement .