This is really interesting to me. I'm from the city that Peaky Blinders is set in, which is Birmingham, and we're known as 'Brummies' over here and have the 'Brummie accent'. I've worked really hard to lose the accent over the years, but it still comes through a bit - especially if I've been drinking.
I heard that there was a survey done about British accents. Brits voted the Brummie accent as the worst, saying it makes the speaker sound unintelligent and slow. Meanwhile, the rest of the world voted it as the best accent; to outside ears it apparently has a nice lilt and flow to it. That's one of the reasons why I have promoted my channel outside of the US to start off with!
Funny how this kind of thing works...