This is a post about accents and dialects. Let's get one thing straight at the beginning. EVERYBODY has an accent and a dialect! There is no such thing as a neutral accent or dialect, but there are some that have been accepted (by whom?) as the norm.
In English, the way of speaking known as Received Pronunciation (RP), or BBC English or The Queen's English is an accent of the South East of the country, which has been accepted so long as some sort of gold standard that people who use it, like me, sometimes state that they don't "have an accent at all." But we do; it's just that ours has been deemed the way everyone "ought" to speak.
Even RP changes. The very clipped version known as XRP (ex-Received Pronunciation) can be heard if you listen to wartime radio news bulletins or the Queen's early broadcasts. This has mutated over time within the Royal Family, so that Prince William's accent is much closer to his non-Royal contemporaries' - even though Prince Charles still pronounces "house" to rhyme with "mice."
If you watch the Netflix series The Crown, you will hear that Claire Foy and Olivia Coleman have modified the XRP accent of the monarch and not precisely imitated it but given a impression of greater formality and inhibition in language which goes well with the role. Of course people do tailor their accents and everything else linguistic to suit their context and companions. This is known as register and maybe we can talk about that another time.
Ex-PM Tony Blair was much mocked for adopting a glottal stop and other aspects of what is disparagingly called Estuary English, in order to sound more like a man of the people. He was also a converger, which I have some sympathy for, since I am one myself. My daughters used to say they could tell who was on the other end of the phone by the accent I adopted while talking to them.
Anyway, accent is different from dialect, because it is about phonology and intonation. Whereas dialect is about vocabulary and syntax. Of course, it's true that people who use a regional dialect will probably have a regional accent too.
The dialect equivalent of RP is Standard English (SE). It is possible to speak SE with a regional accent, whether from this country, the USA, Canada, Australia or New Zealand, without using a different dialect. Nicola Sturgeon, Jacinda Ardern, Justin Trudeau and Joe Biden all speak Standard English but with the accents of the countries they come from.https://www.dialectsarchive.com/england
What is true of English is true of other languages too. If you are an Italian speaker and travel in Tuscany you will hear the distinctive pronunciation of "c"s and "g"s of the locals, so that "Coca Cola" sounds like "Chocha Chola" with a sound like the "ch" in "loch."
There are well-known "dialect poets" like Roberts Burns and William Barnes who wrote as they spoke. And many examples in prose literature, which are hard to read, because they are signalled by a lot of extra punctuation and new spellings (to represent accents). You will find many examples in Thomas Hardy, D H Lawrence, Mark Twain and Harper Lee, but it's fair to say that these last are not using their own speech patterns but those of their less well-educated and lower status characters.
When does a dialect become a separate language? The "Romance languages" (French, Italian, Spanish etc.) began as dialects of spoken Latin. Some people believe that a dialect becomes a language when it acquires a definitive written form.
As a coda to thinking about accent and dialect, there is an even smaller sample than a region: a person's idiolect. (This is, along with zeromorph, one of my favourite linguistic terms). It covers an individual's speech patterns - both accent and intonation, choice of words, characteristic expressions and so on. It is how we can recognise immediately on the radio or in a telephone call a great range of people from celebrities to personal friends.
Word of the week: What else can in be but lockdown? Here in England today is the first of a four week lockdown, meaning not quite what it did at the end of March.