The problem is not just Britain’s stricter immigration rules. Other workers, in Britain and elsewhere, have left the hospitality industry looking for more stable employment, according to Kate Shoesmith, the deputy chief executive of the Recruitment & Employment Confederation, which represents recruitment companies and agencies.

Restaurant and hotel workers, who can’t work from home, have been scarred by unexpected changes in lockdown rules that have pulled them in and out of work at short notice. Despite the success of Britain’s vaccination program, the delta coronavirus variant is threatening to delay the full lifting of social distancing restrictions in England later this month.

Some people “are not confident there won’t be another lockdown,” Ms. Shoesmith said.

Many workers have moved on to less strenuous jobs that don’t require such late nights and long shifts, such as in call centers, retail or other customer service roles. Adecco, a large recruitment agency, sent out a request to tens of thousands of job-seekers to gauge their interest in working in hospitality. Just 1 percent responded.

Ms. Shoesmith said recruiters expect some European Union nationals to eventually return to Britain to work, “but the vast majority won’t; that’s the anticipation.”

To help fill the gap, there is a broad sentiment that the industry must make hospitality an appealing career for Britons, one worth aspiring to, with training and opportunities for promotion. For now, though, this work is often considered just “a job you do in-between other things,” as Ms. Shoesmith put it.

UKHospitality has teamed up with work coaches in government job centers. It wants them to prioritize hospitality as a “career of choice” and think beyond entry level or front-of-house positions.

Until then, the shortage of workers is a drag on countless businesses.

In more than three decades in the industry, John Crompton, the director at Hillbrooke Hotels, said he had never known a staff shortage like this. The company, which has four “quirky luxury” hotels and inns in eastern and southern England, needs to hire at least 50 people.