What makes Jacob Rees-Mogg's accent posh? [closed]

The accent of the British politician Jacob Rees-Mogg is often described as posh, with many people going as far as saying it is an affectation of his. To my non-native speaker ears, his pronunciation of words very rarely deviates from the transcriptions given in the Oxford dictionary, i.e. the pronunciation used by many other people in the UK. So what is it that makes people so unanimously characterise his accent as posh or plummy?

For reference, here's an interview with him.

Solution 1:

With the widespread adoption of creaky voice ('vocal fry') we may have forgotten that it was hitherto associated, in the UK, with the upper class and was used to give the impression that the speaker was rather bored, or couldn't really be bothered to speak to you, or that you yourself were overexcited. (Some examples of his creaky voice: 'upper class' at 1.01", the second 'um' and 'yes' at 1'53")

The perceived authority of a deep voice has been exploited by British politicians from Harold Macmillan to Theresa May. Margaret Thatcher went so far as to hire a vocal coach to change the register of her voice. Jacob Rees-Mogg's voice is not naturally deep, so he needs to creak.

Generally his tone in your clip is carefully uninterested. Bored. It doesn't do to be too enthusiastic.

Specific examples of posh pronunciation:

individuals:individjorls (30"), they're not:nort (48"),class [nasalized] (49"), never met:never mairt (2'22"), so:seəo (2'26"). The cultivated stammer 42-43", 2'29", 2'55-56".