Pretty embarrassing that we don’t know much - at least not me. For me, I can only notice on a macro big level. So someone from Manchester definitely speaks differently than Prince William but I can’t tell the difference between Manchester and Liverpool. When I was in college in DC, the owner of a bar I went to regularly had a ****ney accent as he was from the East End of London I guess and it was hard. Like I had to pay extra attention when he spoke. I know the West End is different and I had friends from affluent parts of London and their English was Roger Moore or later James Bond easy.