Green’s Dictionary of Slang

the best, the ideal.

1841		Spirit of the Times (N.Y.) 25 Sept. 360: Talking of cheese, your present conduct isn’t altogether ‘the Cheshire’ [HDAS].
1849		G.G. Foster N.Y. in Slices 90: Something between a telescope and a pair of goggles is just now ‘the Cheshire’.
1909		J. Ware Passing Eng. of the Victorian Era.