SALFORD, England — Like the majority of voters in this gritty part of northern England, Alan Wood voted for Britain’s withdrawal from the European Union largely, he says, because of immigration.

But lately, as he watches his government’s stumbling efforts to negotiate departure, Mr. Wood has begun to suspect that Britain’s economy will suffer, questioned how he will be affected and wondered whether he made a mistake.

“I honestly don’t know whether it is right or not,” he said, munching a meat pie and fries at Yum Yum’s cafe.

“I didn’t realize how big it was going to be,” added Mr. Wood, 54, a dog trainer, conceding that “if there were another vote, a lot of people would change their minds and vote to stay this time.”