Green’s Dictionary of Slang

1. shrewd, knowing, ‘au fait’.

1829		J.T. Brockett North Country Words (rev. edn) 317: Varment [...] is also a sort of cant word for knowing; as a varment chap, a knowing one .
1835		E.J. Trelawny Adventures of Younger Son I 89: She [a ship] pitches damnably in a swell. Nevertheless there is a varment and knowing look about her which I like .
1852		‘Epistle from Joe Muggins’s Dog’ in Era (London) 18 July 3/4: ‘Game but warmint — werry warmint’.
1860		R. Nicholson Rogue’s Progress (1966) 38: The Duke rode on the box with his varminty* driver [note] * A sporting amateur with professional knowledge; or, cunning, knowing.
1890		‘Rolf Boldrewood’ Colonial Reformer (1891) 340: He [...] ran into the stockyard and caught the varmint, ambling black mare.

2. fashionable, ‘swell’, dashing.

1811		Lex. Balatronicum n.p.: Varment. (Whip and Cambridge.) Natty, dashing. He is quite varment, he is quite the go. He sports a varment hat, coat, he is dressed like a gentleman Jehu.
1824		‘A Pembrochian’ Gradus ad Cantabrigiam 122: A varmint man spurns a scholarship, would consider it a degradation to be a fellow.
1830		Lytton Paul Clifford I 59: Many were the tight apprentices [...] who used to turn back in admiration of Bachelor Bill, when of a Sunday afternoon he drove down his varment gig to his snug little box on the borders of Turnham Green.
1832		Egan Bk of Sports 3: ‘They say that you are the most varmint of ’em all and wish that they had you back again at Newmarket.’ The phrase varmint was a cant term in the days of the merry monarch Charles II, and was frequently used when speaking of him.
1837		Sydney Herald 20 Nov. 5/6: [T]he ambition of all [...] who are desirous to be considered ‘varment’.
1845		‘A Week in Oxford’ in Bell’s Life in Sydney 25 Oct. 4/3: The tightness of their nether garment stretched over their ill-concealed ‘tops and shorts,’ and whose ‘varmint pink’ may be seen peeping out beneath the cuffs of their ‘big bens’.
1853		R.S. Surtees Mr Sponge’s Sporting Tour 31: He’s a varmint-looking chap [...] shouldn’t wonder if he can go.
1854		G.J. Whyte-Melville General Bounce (1891) 326: Bowling merrily down the road [...] behind the ‘varmint’ bay mare.