how London has killed off elements of local dialects across England ?

London accents could be taking over, according to recent research by the University of Cambridge.
The regional diversity in dialects could be diminishing, as research from an app has revealed much of England is falling more in line with how English is spoken in London and the south east.
Cambridge researchers launched the English Dialects App in January 2016, which was downloaded more than 70,000 times.
Thirty-thousand people provided results on how they pronounced certain words and colloquialisms, allowing researchers to map the spread, evolution or decline of certain modes of speech.