I set myself on a path toward U.K. citizenship this year — and so the anti-immigrant riots engulfing Britain and Northern Ireland have left me shaken.

The vitriol and violence focused on the foreign-born may have been sparked by misinformation, but that doesn’t disguise the fact that the tinder was waiting to be lit in a Britain that many natives and newcomers find hard to recognize: reactionary and polarized, instead of civil and embracing.

My colleague Adrian Wooldridge has examined the situation, concluding that Prime Minister Keir Starmer faces tough decisions with his political honeymoon having lasted less than a month. Thuggery cannot be tolerated, but many Britons are bewildered as ever larger waves of immigration transform their cities and towns. The confusion was not helped by five prime ministers vowing and failing to regulate the flow over the past 14 years.