Green’s Dictionary of Slang

1. pudding, dessert.

1909		J. Ware Passing Eng. of the Victorian Era 3/1: Afters (Devon), Sweets — pies and puddings.
1921		N&Q 12 Ser. IX 345: Afters. A second dinner-course, as rice or stewed figs.
1943		R. Llewellyn None But the Lonely Heart 301: There’s some afters coming up.
1947		N. Streatfeild Grass in Piccadilly 169: There was a lot of wonderful stuff prepared for ‘afters’.
1953		J. Franklyn Cockney 290: A Cockney woman is unlikely to ask the greengrocer for goosgogs [...] but quite likely to inform her husband that such a combination is to be the ‘afters’ for dinner.
1959		H.E. Bates Breath of French Air (1985) 192: The party wouldn’t be complete if the children didn’t have custard and jelly for afters.
1960		A. Burgess Right to an Answer (1978) 40: What’s for afters?
1970		H.E. Bates Little of What You Fancy (1985) 565: They still had afters to come: the Christmas pudding and brandy.
1981		J. Sullivan ‘Christmas Crackers’ Only Fools and Horses [TV script] Well, what about the old afters eh?
1991		Dandy Comic Library Special No. 210 11: And what’s for afters?
1996		J. Cameron It Was An Accident 184: Maybe they wanted to purchase a bit of Blue Mountain coffee for afters.

2. in fig. use of sense 1, an extra, a bonus, both negative and positive.

2002

J. Cameron Hell on Hoe Street 262: He went down and they gave him a kicking for afters.

3. after-hours drinking in a public house.

1931

‘English Und. Sl.’ in Variety 8 Apr. n.p.: Having afters — Staying in saloon to drink after time (closing).