Green’s Dictionary of Slang

comfort n.

spirits.

1728		T. Walker The Quaker’s Opera I i: qu.: What hast thou got? poor.: Sir, you may have what you please, Wind or right Nantz or South-Sea, or Cock-my-Cap, or Kill-Grief, or Comfort, or White-Tape.
1833		M. Scott Tom Cringle’s Log (1862) 328: The padre [...] was in the act of swigging off his cupful of comfort [i.e. brandy].

In compounds

comfort shop (n.)

a public house specialising in spirits.

1826

Pierce Egan’s Life in London 29 Jan. 424/2: [A]n old lady toddling out of one of the ‘comfort shops,’ was heard to observe to an ancient companion, that there was some sense in a glass of gin now [i.e. after duty had been reduced]; there was enough of it to do a poor body good.