Pressmark has increased its reserves of steel by half to ensure that it has enough to last 15 days. The coils lie in a corner of the factory, on a grease-stained patch of concrete.

The company borrowed 200,000 pounds (about $263,000) to finance the additional steel. This, combined with a dip in British auto sales, prompted Mr. Nollett to delay buying newer presses.

“Why would we want to invest in a plant if we are going to lose volume?” he asked. “You’ve got the uncertainty over Brexit.”

At Filtermist, which employs about 90 people in Britain, Brexit has posed a distraction from the company’s surging growth. Sales increased by nearly a third from 2017 to 2018, as factories around the world sought to protect workers from the hazards of industrial air. Filtermist automated part of its production and found jobs for the workers displaced by robots.

Mr. Stansfield, the chief executive, does not lack for other worries, among them an economic slowdown in China. But Brexit presents an especially acute danger: Manufacturers could leave Britain for industrial areas in Europe, especially in the key industries of aerospace and automotive. This was the point the Airbus chief brought home.

“He voiced what many people were thinking,” Mr. Stansfield said. “It’s going to affect us.”

Filtermist is owned by a Swedish conglomerate. Mr. Stansfield has grown accustomed to phone calls from incredulous Swedish board members who assume that he, by dint of being English, must be able to divine the mysteries of Brexit.

“They call us and ask, ‘What’s happening? What’s going to happen?’” he said. “And we have to tell them, ‘We don’t know.’”