Green’s Dictionary of Slang

upper n.1

[abbr.]

a member of the upper classes.

[US]Drake & Cayton Black Metropolis 546: The ‘real uppers’ may look askance at ‘the racketeers’ and their wives.
[UK]T.H. Pear Eng. Social Differences 90: While many people use ‘person’ indiscriminately, some ‘uppers’ employ it chiefly in a derogatory sense [OED].
[UK]Listener 21 Dec. 802/1: If a man spoke rather loudly...keeping his vowels open, then he was an Upper. If he attempted this and just failed, then he was a Middle. If..his voice carried the flavour of the area in which he was born, then he was a Lower.
A. Alyssa ‘Opposites Attract’ Ch. 16 on allyswritings [Internet] ‘Sorry. But I don’t want him to act like an upper.’ ‘You’d never know that you were one, by the way you act and dress!’ ‘I like it that way!’ Her mother sighed. ‘Krystah, dear, Derek is richer than all of you children put together. He must learn to act properly!’.