Green’s Dictionary of Slang

1. (also bonse) the head, thus the brain, the mind.

1889–90		Barrère & Leland Dict. of Sl., Jargon and Cant.
1909		J. Ware Passing Eng. of the Victorian Era 42/1: Look out, or I’ll fetch you a whack across the bonse.
1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words 32: Bonce; Head.
1930		(con. 1914–18) Brophy & Partridge Songs and Sl. of the British Soldier.
1943		R. Llewellyn None But the Lonely Heart 242: You’ll have just enough time to get your bonse under your coat when the lumps start flying about.
1950		C. Harris Three-Ha’Pence to the Angel 33: ‘Mavis!’ She [...] turned back, shaking her head. ‘Forget ’er bonce one of these days.’.
1962		F. Norman Guntz 13: As soon as this happened my bonce began to swim.
1976		(ref. to 1940s) R. Barnes Coronation Cups and Jam Jars 124: One of Mum’s heavy pots would come down on your bonce.
1985		A. Payne ‘Minder on the Orient Express’ Minder [TV script] 96: I got a little bang on the bonce.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 282: [I] picture the butcher’s bonce on the tray instead.
1999		Guardian Guide 5–12 June 29: The only frontman daring to sport headwear that has his bonce resembling the erect penis of a giant rabbit.
2002		J. Cameron Hell on Hoe Street 214: Nicky you all right in the bonce?
2021		J. Meades in Critic June 6/2: Post-modernism [...] which, whatever it meant, was really too jolly difficult to get one’s bonce around.

2. a hat.

1914

E. Pugh Cockney At Home 135: ‘I’ll give you woe,’ she says, an’ buries me in my bonce – I mean my ’at.