They wouldn't have come here pre-1950's because most people in the UK lived hard-scrabble lives full of grinding poverty in cold slum houses, doing hard manual work for just enough to feed themselves and their kids. No benefits, no pensions, no "free" medical care, and the ever present threat of the workhouse to keep them in line.
Which is exactly what we're heading back to, at speed. ..in fact, a substantial proportion of us are already there, minus the workhouses, but those will come.
Add in the end of oil and the brutal NW European climate, and the realisation of just how few people the soil here supports, and they'll all be fucking off again when they come to realise just how much better life was back home.
Who would turn up here, of all places, unless they didn't know how deadly this place was? Mind you, half the natives don't even realise, but they will, eventually. Might take a century, might be sooner, who knows, but it will happen.
Poor sods.