The English have an incredibly diverse range of accents, and that was true even before the introduction of so many migrants from foreign shores. If you listen to an English person speak, you will usually be able to tell very quickly which part of the country they are from, especially if they are from one of the major population areas, or a rural area with an especially strong accent. The one accent which is so rarely heard today is the traditional "BBC" accent, so beloved of the educated classes in years gone by. The English seem to have discontinued teaching their young people to speak "properly".
You can still hear upper class accents, especially in Chelsea and other parts of the West End of London, but most of the city speaks quite differently. To be fair, we have also lost the caricatured "Eliza Doolittle" cockney accent as well, as most of the squalor and illiteracy of the Victorian era receded to the Welfare State. Most of London and the South East still uses a form of speech in which the 'h' is missed of the start of words, and 'th' is often replaced by 'f' or 'v' sounds, depending whereabouts it appears in the word. In Cockney London, you can still find rhyming slang used, and many of the best examples of this have become well known amongst people from other regions.
The most populous areas of England outside London are the huge urban conurbations of what were once called Lancashire and Yorkshire. Those counties still exist, but the large cities such as Manchester, Liverpool, Leeds, Bradford and Hull are no longer considered to be within them. Although there is a definite similarity between all Northern accents, including those from even further north in the Tyne Tees area, each individual city has its own accent, and they are all very distinctive. Even over the border in North Wales, you will often hear accents which sound like Liverpool or Manchester, due to the large number of English people living there.
The other major conurbation in the West Midlands has its own distinctive group of accents, and again there is tremendous variation between one town and the next. In Birmingham, which is England's second city, you often hear words such as 'you' pronounced as 'yow'. In the Black Country area to the West of Birmingham the dialect and accent can be so extreme as to be unfathomable to anyone not familiar with it. Most of the land to the West of the Black Country is very rural, and it is amazing how similar the accent is to the rural accent of East Anglia, on the other side of the country. There are differences, of course, but the accents of people from the rural areas are very distinctive.
