Green’s Dictionary of Slang

to burn, to let burn.

1520		Tyndale Works I 304: [...] If the porridge be burnt too, or the meat over-wasted, we say, ‘the bishop hath put his foot in the pot,’ or ‘the bishop hath played the cook’; because the bishops burn whom they lust [F&H]].
1738		Swift Polite Conversation 6: lady answ.: (To the Maid) Why, sure Betty, thou ar’t bewitcht, this Cream is burnt too. betty: Why, Madam, the Bishop has set his Foot in it.
1788, 1796		Grose Classical Dict. of the Vulgar Tongue (2nd, 3rd edn) n.p.: It is a common saying of milk that is burnt to, that bishop has set his foot in it. Formerly, when a bishop passed through a village, all the inhabitants ran out of their houses to solicit his blessing, even leaving their milk, &c on the fire, to take its chance; which, when burnt to, was said to be bishopped.
1811		Lex. Balatronicum [as cit. 1788].
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue [as cit. 1788].
1839		Hereford Times 15 June 4/3: It is a common saying of milk that is burnt to, that the bishop has set foot in it.
1863		E. Gaskell Sylvia’s Lovers I 64: If thou’lt have an eye to th’ milk, and see as it does na’ boil o’er, for she canna stomach it if it’s bishopped e’er so little.