I live in a seaside area (Thanet) which had the first UKIP council in the UK and where Farage lost in the general election in 2015 (first time I had voted Tory

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By then I had been here about eight years. I had retired and was volunteering in an advice bureau. Certainly a lot of people had moved down from South and East London (indeed I did) and the immigrant population were mostly Eastern Europeans. As with a previous poster they did the lower paid jobs - care, hospitality, fruit and vegetable picking
I can say that there was an amount of hostility towards the Eastern Europeans then. We had it expressed to us in the advice bureau - sometimes based on apocryphal stories. IIRC Khan became mayor in 2016 so, in this instance anyway, I don't believe that the stories about what London is like under his rule influence(d) these folks views. They were there already although I guess it maybe reinforces them
Fwiw the UKIP council was awful - fair to say that we have had bad Tory and Labour administrations too.