Working Class Defined

So, what is the official definition of "working class"?

Roget's New Millennium™ Thesaurus
Main Entry: plebeian
Part of Speech: adjective
Definition: lower-class
Synonyms: banal, base, coarse, common, conventional, humble, ignoble, low, lowborn, lowly, mean, ordinary, pedestrian, popular, proletarian, traditional, uncultivated, unrefined, unsophisticated, unwashed*, vulgar, working-class
Antonyms: aristocratic, cultivated, refined
Source: Roget's New Millennium™ Thesaurus, First Edition (v 1.3.1)
* = informal or slang

Makes you wonder what the ignoble lowborn who wrote this entry for Roget was thinking, eh? Mind was fixed on pelf and place (see this, and this) perhaps.