Sloanie (or occasionally a Sloane Ranger) is a stereotypical young upper-middle or upper class person who pursues a distinctive fashionable lifestyle. Probably, the most famous example of this subculture was Diana Spencer, before and around the time she married Prince Charles. Another notable example is the TV character Tim Nice-But-Dim, an Old Ardinian.
The term is a humorous combination of "Sloane Square", a location in Chelsea, London, famed for the wealth of residents and frequenters, and the television character The Lone Ranger.