I lived in England for a while when I was young. Still have very little if any problem understanding them. I have heard it said that the country is roughly the size of Florida but they have 40 something different dialects and someone from Cornwall would have trouble understanding someone from Newcastle.Pendant hat on, here, but it's not a "London" accent. It's an East End of London accent, also known as cockney. Specific to the East end of london only but has since spread. But yeah.