Why do I speak for them? Honestly ask yourself why would I know?
Maybe because when you get older, and specifically when you have kids, you do not want to put up with the sheer volume of people, traffic and hecticness that defines living in a big city. When you have kids you usually need a larger property and the practicalities of bringing up kids , the school run, sleepless nights etc makes commuting a non-option. So you move. I lived in a tent in Biggin Hill and then a shared room in a house in Bromley for about 8 months but I could not have afforded to move into anywhere bigger if I had kids back then. Even though I was earning very good money.
If you think that living in what you consider a typically Old English country town or village is an indication of those moving there being racist (and i know you don't but that is precisely the argument PJW and other racist ex-pats make) then that seems to me to be projection.
Why didn't you ask about Black British celebrity moving out into the countryside?
Big cities even with largely white populations are inevitably going to have more crime, pollution etc.
Billy Bragg is just a bloke from Barking who happens to be a musician whose lives are defined by playing traveling for much of there working lives often to a new town every night for months at a time. He is also a brilliant example of somebody who loves, documents and celebrates England. Why should that mean he has to live in the place where he was born?
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