Green’s Dictionary of Slang

(UK Und.) a highwayman.

1718		C. Hitchin Regulator 19: A Bridle-Cull, alias a Highway Man.
1743		Fielding Life of Jonathan Wild (1784) I 118: A booty of £10 looks as great in the eye of a Bridle-cull [...] as that of as many thousands to the statesman.
1768		(con. 1710–25) Tyburn Chronicle II in Groom (1999) xxvii: A Bridle Cull A Highwayman.
1842		Egan ‘The Bridle Cull’ in Farmer Musa Pedestris (1896) 139: Oh prick up your list’ners if you are fond of fun / A bridle-cull’s the hero, and his little pop-gun.
1897		C. Whibley ‘Jonathan Wild’ A Book of Scoundrels 79: He lived on terms of intimacy with the mill-kens, the bridle-culls, the buttock-and-files of London.