:grins: Oooh that's a politically complex can of worms these days, Dennis

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In simple terms, 'Class' renders down to how much wealth you have (and in what form) and how you go about getting it.
Working Class is the bottom end of the wealth scale and is characterised by manual labour and factory work.
Middle Class is a broad band that sits between Working and Upper Class. Incomes can vary widely and some ownership of property is likely at the upper end. The Class is characterised by what are still termed the Professions - so Doctors, Lawyers, Accountants and so on are considered Middle Class.
Upper Class is the Monied/Landed portion of the spectrum. Incomes can be huge and, perhaps as a signature of the class, are frequently unearned or inherited. The Landed Aristocracy and the descendants of the first Industrialists are Upper Class (with the former considering themselves superior to the nouveau riche upstarts).
Tho' I proudly proclaim myself to be Working Class, I suppose what I do for a living nudges me into the muddy hinterlands of Middle Class - maybe not. 'Technical' rather than 'Traditional' professions are a bit fiddly in the old social scale. My income level is definitely Working Class - engineers are not well rewarded if, like me, they do all they can to avoid managerial responsibility.