The Newcastle striker Alexander Isak was born and raised in a settlement just north of Stockholm city centre called Solna. He played football in his native Sweden, followed by stints in Germany and Spain, before moving to Newcastle last year. He has never lived in London. You would not guess this from his voice.

In a recent clip in which he is speaking English, Isak sounds as if he were raised in Lewisham or Tottenham, Croydon or Bethnal Green. To use a modern idiom, he sounds like he is from the endz. Which is another way of saying that Isak speaks English with a multicultural London English accent (MLE), the dialect of young ethnic minority people in London and the south-east of England, popularised by grime music and TV shows such as Top Boy.

MLE is increasingly spoken by young white Londoners too. Zachariah Noble, a recent contestant on the ITV show Love Island, is a young white man from south-east London; he sounds like a “roadman”.

MLE has risen in line with the decline of the accent that hitherto distinguished working-class Londoners: cockney. Most working-class, young, white British people in southern England today either speak MLE or the accent that characterises working-class white people in Essex and Hertfordshire: estuary English.

A recent study by linguists Amanda Cole from the University of Essex and Patrycja Strycharczuk at the University of Manchester has found that cockney and received pronunciation are vanishing among young Britons and being replaced by MLE, estuary English and standard southern British English.

Cole and Strycharczuk recorded the voices of 193 young people between the ages of 18 and 33 from south-east England and London, and built a computer algorithm to listen to how they spoke. They then grouped them by how their participants pronounced vowels in different words: 26% spoke estuary English; 49% spoke in standard southern British English; and 25% spoke in MLE.

Some of these changes are the consequences of positive aspects of the 20th century: the wider expansion of education and the decline of socioeconomic segregation. More recently, they reflect the fact that young people watch the same TV shows and listen to the same music; accents are no longer rooted to a narrow locality. They bring people together more than they divide.

As Cole wrote in a recent column for the Conversation: “Notably, standard southern British English and estuary English are not as different from each other as cockney and received pronunciation.” She added: “This could be evidence of what’s known as dialect levelling – where young people from different parts of the region now speak more similarly to each other than their parents or grandparents did.”

That the gap between working-class and affluent accents is closing is good. Speech is one of the most invidious hallmarks of class distinctions in British society. The Irish playwright George Bernard Shaw, in his preface to Pygmalion, wrote that “it is impossible for an Englishman to open his mouth without making some other Englishman hate or despise him”. Pygmalion explores how a flower girl with a cockney accent can become posh under the tutelage of a linguist. A modern-day Eliza Doolittle will have a smaller gap to close: between estuary English and standard southern British English.

But these changes in the speech patterns of British people nevertheless mask a distinct loss: the vanishing of regional accents. One study by HSBC, for instance, found that by 2066 many accents in the north of England will considerably tone down and potentially die out.

Another Newcastle striker had a fascinating voice. He was not from Sweden. But neither was he from Newcastle. He was called Jackie Milburn and he played in the 1940s and 50s. He came from Ashington, a coal-mining town in Northumberland, and he spoke a dialect called pitmatic. Even the very name of this dialect evokes the coal mines that marked this part of the north-east of England. Milburn played in a Britain with far less racial and religious diversity than today. But he played at a time with far more diversity in terms of regional accents.

This accent he grew up with has all but vanished. Milburn is not even the most famous footballer to come from Ashington. Bobby Charlton, who died last month, also grew up there. Milburn was a cousin of Charlton’s mum.

In the 1970s, Melvyn Bragg presented a programme called Word of Mouth that explored the various ways of speech in the UK. In one episode in August 1976, it looked at a rural village in Northumberland, and we can see a group of male farmers shearing sheep, eating sandwiches and speaking in their local Northumberland dialect. I can barely understand a word of what they are saying.

England has been a unitary state for more than a thousand years but has been a patchwork of dialects until relatively recently. John Clare, the Romantic poet from Northampton, once declared: “I could not fancy England larger than the part I knew.”

But when it comes to languages, change is the norm; things never stay the same, and it would be pointless to expect them to do so. Researchers from the Australian National University have found that by the end of this century 1,500 languages in the world will be extinct. Other researchers say that between 50% and 90% of the world’s languages could be extinct in the next 100 years. The decline of regional dialects makes sense in this context.

Yet I can’t help but feel a pang of loss. These accents are not simply ways of pronouncing words; they contain within them a rich reservoir of sayings, aphorisms, slang and poetry. In the future, no one will embody them in speech; they will simply be relics of a lost world, like trinkets or fabric displayed in a museum.