1781, “a shoemaker, a shoemaker’s apprentice,” of unknown origin.
It came to be used in Cambridge University slang c. 1796, often contemptuously, for “townsman, local merchant,” and passed then into literary use, where by 1831 it was being used for “person of the ordinary or lower classes.” Meaning “person who vulgarly apes his social superiors” is by 1843, popularized 1848 by William Thackeray’s “Book of Snobs.” The meaning later broadened to include those who insist on their gentility, in addition to those who merely aspire to it, and by 1911 the word had its main modern sense of “one who despises those considered inferior in rank, attainment, or taste.”
Inverted snob is from 1909.
Then there is that singular anomaly, the Inverted Snob, who balances a chip on his shoulder and thinks that everyone of wealth or social prominence is necessarily to be distrusted; that the rich are always pretentious and worldly, while those who have few material possessions are themselves possessed (like Rose Aylmer) of every virtue, every grace. [Atlantic Monthly, February 1922]