British expats in Maine reacted with sadness and disbelief Friday to the stunning win by Brexit supporters at the polls in the United Kingdom on Thursday.

“It really is a terrible, terrible mistake of mind-boggling proportions,” said Philip Jones, a Yarmouth resident originally from London.

Earlier this week, some U.K. citizens living in Maine said they were watching the referendum to leave the European Union closely, but none planned to vote. The general sense was that voters would remain in the EU, although the vote would be close.

The results Thursday shattered those expectations.

“I think there was some naiveté. We thought surely people would come to their senses,” Jones said. “It was so clear that it was the right thing to stay, it is inconceivable that 52 percent of the population was in favor.”

Jones and others fear the result of the vote could spell economic and social catastrophe for the U.K., or even split the union entirely. In Scotland, where voters heavily favored remaining, nationalist politicians are already planning for a repeat of a 2014 independence referendum. Sinn Fein, the nationalist party in Northern Ireland, also called for a vote to unite with the Irish Republic.

“One of the ironies of the whole situation is the reason for leaving was to put Britain first, but it might lead to the break-up of the country,” Jones said.

Daniel Bookham, a U.K. citizen who has lived in Maine for the last two decades, also was saddened by the result, saying the vote is a reflection of people who are scared by a changing world around them.

“You can’t really say, ‘Stop the world, I want to get off.’ But that is what voters did,” Bookham said. He worries that British youth, who overwhelmingly voted to remain in the EU, will be most affected by it.

“The people who have to live with this decision the longest were the ones voting against it,” he said. “It is deeply unfortunate, deeply selfish.”

Bookham was opposed to Scottish independence in 2014, but said his view has changed overnight. Thursday’s referendum showed the English voting for their self-interest, he said, so he cannot oppose Scots voting for theirs, even if it would mean independence.

“I hate the idea of it, but it is perfectly in their right to do it,” Bookham said.

Henry Laurence, a political science professor at Bowdoin originally from England, had predicted the remain-in-the-EU side would win with a thin margin.

“I’m still in a state of bewilderment,” he said Friday.

Laurence said the vote will mean short-term financial problems, an expensive and difficult process to disentangle from the EU, and a probable vote on Scottish independence. But, at the same time, he dismissed more nightmarish predictions of financial collapse and possible violence in Europe.

“It is not going to lead to the destruction of western civilization,” Laurence said.