Accents might be seen as the failure of speech to match some imaginary norm. What’s odd in Glasgow seems ordinary in Essex, and vice versa; and what was ordinary yesterday seems extraordinary now. In Ma’am Darling, Craig Brown’s recently published (and very entertaining) biographical study of Princess Margaret, the author devotes a chapter to the princess’s stilted encounter in 1981 with Roy Plomley on Desert Island Discs. “Ma’am, have you a big collection of records?” the presenter begins reverentially. “Ears, quate,” says the princess. “Have you kept your old 78s?” Plomley ploughs on. “Oh, ears,” the princess replies, “they’re all velly carefully preserved.”

The “ears” is baffling until Brown discloses that that’s how she says “yes”, just as she says “nyair” for “no” and “velly” for “very”; and of course the short “a” now commonly rendered as an “e” in comic transcriptions of Brief Encounter: “Eh hev them up in the ettic, eckshleh,” HRH says when Plomley wonders where her 78rpms are kept. Or rather, that’s what Craig Brown hears. When I find the recording of that episode in the BBC archive, I hear something different. “Yes” sounds more or less like “yes”. No matter how often I say “ears” aloud, I can’t hear a “yes” lurking inside it.

Who wants these days to sound posher than the family they were born into? One man at least: Jacob Rees-Mogg

Then it occurs to me that, having grown up in Scotland, I sound the “r”. People in England tend to skip the “r” as the final consonant and say “ee-uh” or “ee-ah”. To them this pronunciation is standard. So to reach an understanding of the princess’s pronunciation, we must also understand the author’s. Sure enough, when I try “ee-uhs”, I catch the “ya” that’s often present in the upper-class affirmative, spoken from the back of the throat – and there is, of course, something of that in Princess Margaret.

Many fewer people speak this way now, and almost none of them can be heard with any regularity on television or radio unless as the subjects of documentaries on impoverished aristocrats, secret fox hunts or elephant polo. The Queen herself no longer sounds as she did – compare last year’s Christmas speech to the one she made in 1957. Like priests abandoning Latin or pundits Sanskrit, what was once known as British “society” has, consciously or otherwise, rejected a form of pronunciation that was exclusive to them, in a vocal effort to blend in with the social classes lower down the scale. This could be read as a failure of confidence, or a way of protecting their position by demonstrating that they are really just like the rest of us. Probably it’s both. George Bernard Shaw writes in the preface to Pygmalion about the impossibility of an Englishman ever opening his mouth “without making some other Englishman hate or despise him”. And who in a democratic-turned-populist age would want to go on living as an advertisement for privilege when a few lessons from a voice coach – of the kind taken, for example, by Samantha Cameron – could help maintain or increase their public esteem?

Until the 1960s, it was the other way around. Accents were continually upgraded. “An honest and natural slum dialect is more tolerable than the attempt of a phonetically untaught person to imitate the vulgar dialect of the golf club,” Shaw wrote in the same preface (a less well-known sentence, in which the Irish playwright displays the snobbery he was chastising the English for a paragraph or two before). But not many working-class people shared that view. It was good to speak proper: you got on that way.

Elocution lessons were one way to progress – “how now brown cow”, and so on – though it would be wrong to stress their importance. Trying to understand why I speak differently from my parents, I can think of some reasons that are particular to me – for instance, leaving home in Fife for Glasgow when I was 18, and leaving Scotland for London seven years later – as well as others that were widely shared in my generation. Schoolteachers, the radio, the cinema: all these played their osmotic part. We absorbed an idea of “pure” or standard English that was exemplified by the way officers spoke on the bridge of HMS Compass Rose, or Dirk Bogarde in Doctor in the House.

Facebook Twitter Pinterest Dirk Bogarde in Doctor In The House. Photograph: Rex Features

Voices that deviated from this standard (such as cockney, Highland, Welsh, north country) usually signified personality types (chipper, melancholy, talkative, bluff) rather than complicated individuality.

As this was Scotland, a place of strong dialects that some now argue amount to a separate language, vocabulary as well as accent was worn away. I can’t ever remember using words that my parents used: bairn for child, bide for stay, blate for shy, breeks for trousers, brig for bridge (to name a few of the Bs). An aunt, who had left Fife as a girl to do well in London, would sometimes trot out old aphorisms when she came north to see us: “They keep their ane fish guts fir their ane sea maws [seabirds],” she’d say of some tight-fisted or self-interested group. But the effect was odd. London vowels mixed with Scottish consonants. It was like looking at some piece of folk art in a museum, encouraging the notion that the dialect was ill suited to modernity.

In England, other than in the big-city patois developed by the multicultural young, I think that notion still holds good. Dialects are certainly paid attention. This week the Leeds Archive of Vernacular Culture announced it was to receive a National Lottery grant of nearly £800,000 to help with its survey of English linguistic traditions; and next month The Arsonists, a new opera to be sung entirely in the Yorkshire accent, will have its premiere in Salford. But however worthwhile the result, these ventures have the same air of scholarship and hobbyism associated with enthusiasms for canal boats, preserved railways and brass bands. The country where accents are genuinely resurgent is Scotland, where they have political clout. And in one particular case, that of the Glasgow accent, have thickened rather than weakened.

A comparison of Scotland and the West Midlands region is instructive. Both contain similar numbers of people, but while Scottish-accented reporters and presenters are ever present on BBC news programmes, it’s hard to think of any regular voice from Birmingham. A knotty cluster of reasons may explain this, including the fact that middle-class Scots tend to retain their local accents while middle-class Midlanders tend to shed them but the suspicion that politics has empowered the Scottish accent is hard to avoid. When the TV presenter Tessa Dunlop presented an idea for a documentary about Ben Nevis to Radio 4, concerns were raised about her sounding “too English”. In fact, she was born and raised in Scotland, and in a recent piece blamed the BBC for kowtowing to “that last acceptable whipping boy of national identity – the accent … every lazy xenophobe’s best friend”.

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Anglophobia certainly exists in Scotland, and the “slightly posh-sounding English” that Dunlop says she speaks probably does make her inimical to the more bigoted nationalist. But in England too that voice has lost friends. Who wants these days to sound posher than the family they were born into?

Well, one man at least. How did Jacob Rees-Mogg come to sound as he does? “Top school” and “family background” won’t do as explanations. Etonians don’t as a rule drawl like that, at least not in the past half-century, and there are no dukes and earls in his lineage. His mother, Gillian, went to Camden School for Girls, a good grammar in north London, and then to secretarial college; his father, William, was born into the Somerset gentry and attended Charterhouse and Balliol College, Oxford. They met at the Sunday Times in the early 1960s, when William was the city editor and Gillian his secretary. A colleague at the paper, Hunter Davies, remembers William as good journalist (he later edited the Times): no drawler, but rather aloof and too work-absorbed to notice that his secretary was secretly in love with him – until, that is, Davies pointed it out.

A shy man married a jolly woman. Jacob was the fourth of five children. He had some of his father’s accent but little of his shyness. His persona probably combines his mother’s sense of fun with his father’s self-importance, but to a large extent he’s self-invented. The theatrical drawl and the good suits make him a retro figure who seems to come from an older England of accents and classes, layered like geological strata, everyone knowing their place. His supporters, who know they can never sound as fine as he does, are drawn like moths to a most superior lamp.

His rise is the great exception to the demotic progress of the English accent; the old dialect of the upper classes may not be quite done for yet.