It is a division as entrenched and as bitter as the split between Brexit backers and EU Remainers – though in this case, the issue is truly personal. Do you pronounce the word “scone” to rhyme with “cone”, or to rhyme with “gone”?

To those in the latter group, it is a posh affectation to use a long vowel for this staple item of afternoon tea. By contrast, those in the former group believe they are merely following a logical extension of the pronunciation of the word cone by adding an s as a prefix.

The example of scone’s different pronunciations underscores the highly varied nature of Britain’s complex, shifting patterns of speech, and comes as the nation celebrates English Language Day and Shakespeare’s birthday on Sunday. It also marks the 100th anniversary of the publication of Daniel Jones’s English Pronouncing Dictionary, which tracks how spoken English has varied in terms of geography and over time.

In fact, the way you pronounce scone says far less about your class and much more about your geographical origins – for, according to “The Great Scone Map”, produced by Cambridge University academics, its pronunciation follows a discernible pattern across Britain and Ireland. Those who rhyme it with gone predominate in Scotland, Northern Ireland and the north of England. Those who rhyme with cone dominate in southern Ireland and the Midlands. The rest of the country is a mixture of the two pronunciations.

And, just to complicate the matter, there is a third pronunciation available for the word – in the form of the village of Scone in Scotland, which is pronounced “skoon”.

“It is not a matter of being posh, or thinking you are posh, if you pronounce scone as in cone,” says phonetics expert Professor Jane Setter of the University of Reading, co-editor of the English Pronouncing Dictionary. “It is more a matter of where you grew up. By and large, the pronunciation that rhymes with gone is more common, however.”

“Our language continually reshapes itself,” she says. “New words appear. In addition, pronunciations of existing words alter. The word trap used to be pronounced more like ‘trep’, for example. Similarly pat was pronounced more like ‘pet’. Changes like these have been tracked in our dictionary for a century now – though very often when we detect changes, we really don’t understand why they have taken place.”

Consider the words poor and pour. “In the past they were pronounced differently and still are in some areas,” says Setter. “However, as time has passed, more and more people, myself included, have come to pronounce them in the same way – as in the word ‘pore’. In phonetics, it is called a merger, but we don’t always know why it has taken place in some areas of Britain and not in other parts of the country.”

Other entries in the dictionary have been pronunciations that have virtually disappeared from the modern world. The word calibre – as in the quality of a person’s character – is now pronounced as “KAL-ih-ber”. “Fifty years ago, you would have been far more likely to pronounce it as ‘ka-LEE-ber’,” said Setter.

‘Am I Bovvered’? Catherine Tate’s character Lauren follows a trend in replacing ‘th’ sounds in words with ‘f’ or ‘v’ sounds. Photograph: BBC/Tiger Aspect/Tiger Aspect

An even more striking illustration is provided in England by the word “arm”. In 1950 most people living to the south-west of a line drawn between London and Birmingham – as well as pockets in Lancashire and in Northumberland – pronounced the “r” in “arm”. The vast majority of those living outside these areas did not. Today virtually everyone in England now pronounces arm without the “r” – though people in Scotland, Northern Ireland and the Republic of Ireland still use it.

“This latter trend has become quite pronounced,” adds Setter. “A similar pattern has been noted with the word ‘square’ and also with ‘near’. Essentially, in England, we no longer pronounce these words with an ‘r’ in them either. We say something that is more like ‘squih’ and ‘nih’ today.”

The tendency to enunciate the letter “r” everywhere it appears in the spelling of a word is known as a rhotic accent and it is typified by people from Scotland and Ireland. However the use of the rhotic “r” was once more widespread in England, particularly in the south-west, but this has slowly disappeared.

Similarly the pronunciation of the letter “t” in words like metal is disappearing and is being replaced by glottal stops, in which a stop sound is made by rapidly closing the vocal cords. In this way, the word butter has ended up with a pronunciation like “bu’er”.

In a similar fashion, the pronunciation of “th” inside a word is disappearing and is being replaced by a “v” or “f” – to give us pronunciations like “muvver” or “bruvver” or even “bovvered” – the word so beloved of Catherine Tate’s schoolgirl character Lauren.

In fact, some experts believe that in 50 to 100 years the use of “th” in popularly spoken English will have disappeared. “The idea horrifies some English language teachers but at the end of the day we have to accept that words and their pronunciation are flexible and changeable,” says Setter.

“They are not fixed entities to be enshrined in stone.”

“One of the most profound influences is undoubtedly the London accent, which has a noticeable glottal stop,” she says . “It is the language of the capital, after all, so it is certainly going to affect the southern part of Britain. And you can trace the spread of the glottal stop and other features of the London accent moving westward along the M4 over time. Correspondingly, the rhotic “r” of the Berkshire accent has been lost over the years.”

And that is the crucial point, she adds. “Language changes – and for a variety of reasons. Incomers can affect it. Those who we perceive as being prestige figures or groups can affect it. There are plenty of reasons.