The joke goes like this.

A middle class man living in London opens the door to a plumber, who he has called to fix something in his home.

The pair start a conversation, and before long the first man finds himself talking in a peculiar way.

"Yeah I dunno what 'appened mate" he blurts out as he points at the dishwasher. "The fackin' thing just stopped workin'!"

The working class man smiles politely and gets on with his work, while the middle class man retires to his bedroom, shudders with embarrassment, then recalls the whole episode in a self-deprecating anecdote at his next dinner party.

There is nothing the British middle classes are more obsessed with than poking fun at their own social awkwardness, and nothing is quite as quintessentially, fist-chewingly middle class as the phenomenon of the changing accent.

Whether it's talking to a taxi driver like you're just anutha geezer or suddenly polishing your vowels while sat in a posh restaurant, we cringe at ourselves for modifying our accents because… why exactly? The idea it makes us fake? Or self-loathing? Or simply, that it reveals we're too insecure to be ourselves?

As someone whose accent swings like a weather vane depending on the prevailing social wind - from native Northumbrian to Geordie to a bland London-approximation people back home simply call 'talking all Southern' - I decided to try to find out the truth about bidialectalism (being able to speak with two accents), why it happens and whether we should really be ashamed of it.

Dr Damien Hall, a linguistics expert at Newcastle University who has carried out research into bidialectalism and its causes, starts off by reassuring me a changing accent is very rarely calculated or contrived.

"Bidialectalism is almost always subconscious. Doing it consciously is very hard indeed," he explains.

"Subconsciously, you always have the impulse to adapt to your surroundings, wherever you are. So in London you've adapted the way you speak to a lowest common denominator accent – in other words, you've learned to speak without any regional peculiarities at all that would make you difficult to understand. When you go home, you take yourself out of the professional milieu and back to friends and family members who know you well. You relax, because there isn't that constraint of needing to be understood."

It's a relief to hear him confirm what us tortured accent chameleons have always quietly felt: that we don't do it 'on purpose', that we're not, like the man in the joke, insecure phonies pretending to be something we're not.

Why is it then, I ask him, that bidialectalism seems to be reserved to the middle classes, while people with very upper class or strong regional accents don't seem to change how they speak no matter who they are with?

The answer to this is not, as we've long feared, some fundamental mental weakness inherent to the middles classes, but plain old social mobility.

"Traditionally, people who are labeled 'working class' are more likely to stay where they're from, surrounded by people with the same accent. There is no outside impulse at all to change how they speak," Dr Hall explains.

"By contrast, there are far fewer upper class people who have a regional accent to start with. Most speak a form of Received Pronunciation, which is a social accent rather than a geographical one, and doesn't change whether you're North, South or anywhere else."

"I am not sure you could label it intelligence..."

In other words, both the working poor and the powerful elite, through geography or the social exclusion of others, have historically stuck with their own, and their accents have stuck with them. When the new middle classes began to emerge in the wake of the industrial revolution, a growing ability to travel, work and study in new regions meant they developed the ability to adapt how they speak accordingly.

Suddenly, my ever-changing vowels and constantly rotating line up of colloquialisms is starting to sound like the mark of a shrewd social survivor, rather than a sniveling social sycophant. Perhaps, I suggest hopefully, it's actually a mark of intelligence?

"I am not sure you could label it intelligence," Dr Hall corrects me. "It's generally true for any skill that the more practice and exposure you have to different ways of doing it, the more that skill will improve. People have different capabilities for learning language, but we're all very good at it if we get the chance."

There is another layer to the changing accent problem, and it runs inverse to how we normally talk about it, probably because it's less often a source of embarrassment. On the occasions I see friends I grew up with – particularly when we meet in London – we seem to subconsciously adapt an even broader Northern accent than the ones we had as kids.

This, Dr. Hall explains, is the other part of the explanation for why some people have strong accents and others don't: social identity.

In 2008, he and a team from University of York conducted a study called 'Accent and Identity on the Scottish-English Border'. One of the aims was to establish why two people from the same region, with the same level of exposure to outsiders, could grow up with different strengths of accent. They discovered that self-perception was an important factor.

"We asked lots of questions designed to see what the individuals would do in certain situations where patriotism would matter. For example, you'd ask the Scots, if there was going to be a referendum on independence (this was years before we knew there was actually going to be one), which way they would vote.

"We found there was a a strong correlation between those who said they'd vote 'yes' for independence and those with a very identifiably Scottish accent. In other words, the more patriotic they were, the more pronounced their accent was. Those who didn't particularly care spoke with a more neutral accent."

Perhaps then, after all those neutered conversations with our new London friends, me and my group of fellow dispossessed North-Easterners wandering around Hyde Park sounding like the cast of Byker Grove is a simple, defiant attempt to reclaim our identity. As Dr. Hall puts it: "People use language to establish bonds. But conversely, they also us it to establish barriers."

Whatever is controlling your accent, whether it's geography, personal identity, or – as has always been my hunch – the fundamental, rudderless feeling that comes with belonging to neither tribe at the opposite ends of our country's uniquely entrenched, all-pervasive class system – the truth is that it is probably fading out.

"There is already a dilution of regional accents taking place in the UK," says Dr. Hall. "In 30 years, the North East accent, for example, is forecast to become part of the general 'North' accent."

It's an effect linguists call 'levelling'. As the world becomes more connected and movement between areas more common, regional colloquialisms and variations in speech pattern are dying out, meaning this particular middle class anxiety may one day die out, too.

The lesson, perhaps, is to enjoy your accent while it lasts – whichever one you happen to be speaking today.

This article was first published in 2014.

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