Dr Geoff Lindsey is an authority on phonetic variation in the English language.
This one is spot on.
A tangential observation:
I think it's refreshing that these days it's not necessary to fit into any linguistic straightjacket to be taken seriously. Expert opinion taken seriously can be heard from people of all kinds of backgrounds. The same goes for leadership.
In my native language, regional accent plays no role as a marker of status. It never has. Command of the standard variant of the language does. This is why you have talking heads on television with accents all over the place but with standard diction and grammar.
This clip of an interview of the philosopher and mathematician Bertrand Russell from 1959 is remarkable in the sense that there is probably no one alive who speaks that way but the message is a timeless gem:
