Green’s Dictionary of Slang

churl n.

In phrases

put a churl upon a gentleman (v.) [the supposed links of social class and drinking habits]

1. to drink beer or malt liquor after drinking wine.

[UK]B.E. Dict. Canting Crew.
[UK]Grose Classical Dict. of the Vulgar Tongue.
[UK]Lex. Balatronicum.
[UK]Egan Grose’s Classical Dict. of the Vulgar Tongue.

2. to drink ale immediately after drinking wine.

[UK]Swift Polite Conversation 74: lord sm.: Tom Neverout, will you taste a Glass of the October? nev.: No, Faith, my Lord, I like your Wine; and I won’t put a Churl upon a Gentleman: your Honour’s Claret is good enough for me.