sworn at Highgate, phr. — Green’s Dictionary of Slang

sworn at Highgate phr.

[‘a ridiculous custom formerly prevailed at the public houses in Highgate (then a village north of London), to administer a ludicrous oath to all travellers of the middling rank who stopped there. The party was sworn on a pair of horns, fastened on a stick, the substance of the oath was never to kiss the maid when he could kiss the mistress, never to drink small beer when he could get strong, with many other injunctions of the like kind to all of which was added the saving clause of “unless you like it best”’ (Grose, 1785)]

clever, smart; resistant to illusion or the second-best.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1793		Northern Star (Belfast) 27 Mar. 2/4: The people might be sdaid to be [...] sworn at Highgate, they would never take any counterfeit, while they could have reality.
1811		Lex. Balatronicum.
1822		‘Geoffrey Crayon, Gent.’ (Washington Irving) Bracebridge Hall q. in Galignani’s Mthly Rev. Aug. 241/1: Men who have seen the world, and been sworn at Highgate; who are used to tavern life; up to all the tricks of tapsters, and knowing in the ways of sinful publicans.
1827		Morn. Chron. (London) 25 June 3/4: All future candidates shall prouce a certificate of having attended two courses of Lectures on Midwifery; they might as well have decreed that they should bring a certificate of having been sworn at Highgate.
1836		Yorks. Gaz. 21 May 2/7: He might have sworn not to cut a slice of green cheese from the moon, [but] the oath was just as farcical as being ‘sworn on the Horns at Highgate’ .
1857		Dundee Courier 14 Jan. 2/7: They are all flaming free traders [...] opposed to restrictions of all sorts, and sworn at Highgate — ‘to buy at the cheapest market and sell at the dearest’.
1868		Bury & Norwich Post 24 Nov. 8/2: The Coronation Oath reminds me of the way in which our grandfathers [...] used to be sworn at Highgate. The burly host of the inn [...] administered an oath with a saving clause, to this effect — ‘Will you swear that you will not drink sherry when you can get port — unless you like it better?’.
1883		Morn. Post 11 June 2/7: Both propose for the young man [...] but whether because he had been sworn at Highgate [...] certain it is that Cecil prefers the mistress to the maid.
1890		Manchester Times 5 Sept. 7/2: Will any of your readers tell me where I can find the rigmarole callled ‘Sworn at Highgate.’ It began [...] ‘Never take a bye road when you can take a high road...’.