Green’s Dictionary of Slang

an upper-class person.

1882		W.A. Baillie-Grohman Camps in the Rockies 9: The frontiersman calls them, as we have heard, ‘top-shelfers’; they are accompanied by their servants from England.
1899		Morn. Post 28 Dec. 2/3: You ain’t quite the top-shelfer you think you is.