The relatively new Youtuber known as ‘KoreanBilly’ has posted a variety of videos with some comparing and contrasting the differences between various British accents in the UK as well as offering advice to those who wish to learn English themselves.
He was also recently written about in a Mirror article that covered his video on British dialects, you can read more about it here.
He mentioned in a Q&A video that he was an exchange student in the UK which explains his fluency and explains that he learnt how to speak British English as he was interested in the culture, here’s another one which goes over the differences between the London and Liverpool accents!
