I've never enjoyed the felicity of Professor Higgins in being able to distinguish an inhabitant of Limehouse from one from Bow, but the distinct differences between an Ipswich accent and a Suffolk one, and between a Suffolk and a Norfolk accent were always clear. In London, I can still pick out an Anglian voice in a noisy and crowded pub and gain comfort from it - much, I suppose, as men did in Kit Marlow's day when rapid agglomerations of those regional loyalties, often with knives drawn, protected strangers in London's inns and taverns. And after a few years here, the accent of North London sounds quite different to that of South London despite being separated by no more than the width of the Thames.
So I'm happy that regional accents are thriving. Accents are about identity; identity is about locality. Accents are a rejection of the homogeneity of the Leviathan State in favour of difference and diversity. As Pakistani moslems with thick Bradford accents travel outside that town to discover that it's their accent, not their colour or their dress or their faith, by which they are primarily identified then they cannot help but strengthen their own Bradford identity; a couple of generations of this will dilute jihadism away far more effectively than State measures ever can. Our Bradford moslem will take more comfort from the sound of an 'infidel' Bradford voice in a London crowd than he will from the Prophet, and this is good.