Researchers looked at a distinctive feature of the accent, a "strong R" sound at the end of some words, known as rhoticity.

Commonly used at the end of words like purr, car, bird and her, it's a linguistic quirk that is now rare in younger people, and "may be lost in the next few generations", according to study by researchers at Lancaster University.

Dr Danielle Turton said: "Accent change is often like a puddle: it dries up in most places and leave remnants around the edges."

The study found the "R" in the spelling for speakers from these areas means it should be pronounced like an "R" at the beginning of a word, rather than just creating a longer vowel.

Prominent Lancastrians including comedians Eric Morecambe and Les Dawson, actress Jane Horrocks and Bullseye presenter Jim Bowen are known to use a "strong R".

Dr Turton said Lancastrian speakers "usually differentiate between pairs of words such as 'stellar' and 'Stella', whereas most of England would consider them to be the same".

Hundreds of years ago, using a "strong R" was common throughout England.

One place the feature survives is Blackburn, where the study found, young speakers do mostly say the "R" sound, but they are phonetically very weak and often difficult to perceive.

The habit persists more in older speakers.

Dr Turton said: "For the youngest speakers in Blackburn, these Rs are very weak, which raises the question of whether future generations will even hear these weak Rs at all, and whether this distinction will eventually fade away."

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Her paper - An Acoustic Analysis of Rhoticity in Lancashire - published in the Journal of Phonetics - is the first systematic acoustic analysis of a rhotic accent in present-day England.

Dr Turton said the disappearance of the accent might be happening "so gradually that people don't notice it".

She added: "In the next few generations, this traditional linguistic feature may be lost."

Three years ago, researchers found northern accents were becoming more similar, with the existence of a general northern English accent among "educated people" in the North.