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LONDON — The National Health Service has been described as the closest thing Britain has to a national religion. Created after World War II, the NHS provides free health care to all U.K. residents.

But even before Britons voted to leave the European Union, the financially strapped NHS was beset by workforce shortages. It has long relied on foreigners to fill its ranks, with around 5 percent of its staff coming from Europe.

Now Brexit — Britain's departure from the 28-country bloc in March 2019 — is making matters worse, particularly among general practitioners.

The NHS is so beloved that part of the opening ceremony for the London 2012 Olympic Games paid tribute to its workers. Jae C. Hong / AP, file

The fall in the value of the pound and the perception that Britain is less welcoming to foreigners has made both recruiting and retaining European staff a challenge. Many E.U. citizens living in the U.K. not only feel rejected but are wary about what the future may hold for their status as immigrants.

“This is our home. We are not here as tourists," said Hubertus von Blumenthal, a general practitioner from Germany who is based just outside Cambridge. "With the referendum that all changed. We woke up in the morning and it felt like the rug was pulled from under us."

Von Blumenthal, 56, has lived in the U.K. for as long as he did in Germany. He arrived at 28 to work as a doctor, but is now planning to retire early from the NHS and is looking for a job in Germany, Switzerland or Luxembourg.

Britain came to a draft agreement with the E.U. in December that the rights of the 3 million E.U. citizens living in the U.K. will be enshrined in law and enforced by British courts. Details of the plan are unclear, however, and von Blumenthal for one remains suspicious.

'Bargaining chip'

He said he would make a final decision on whether to move in the next year, before Brexit negotiations are likely to conclude.

"I have no confidence or trust whatsoever [in the government] and feel as much a bargaining chip now as before," he said, adding that his wife recently found a job with a company with an office in Germany so the family can relocate more easily.

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He’s not alone in his deliberations. According to a survey of doctors from E.U. countries working in the U.K. taken by the British Medical Association, 45 percent are considering leaving. Another 18 percent have already made plans to leave.

A hospital in London. WILL OLIVER / EPA

“I have been working and living here for 23 years, paying taxes, and all of a sudden I’m getting told I might have to apply for a work visa, or jump through flaming hoops to stay for a limited time,” said Andreas Herfurt, a 53-year-old GP in the Scottish Highlands.

He came to Britain in 1994 from Mainz, Germany, and is considering moving back, depending on how the Brexit negotiations work out.

The potential loss of such doctors threatens to put even more pressure on a health service that is already understaffed. Prime Minister Theresa May was recently forced to apologize to tens of thousands of patients whose operations were canceled to free up staff and beds to deal with emergency patients.

About one-third of government spending on public services is spent on health, but the pressure from tight budgets, an aging population and increasingly complex medical needs have left many hospitals struggling.

Related: Professionals Wave Goodbye to U.K., Head to Europe

There are currently the equivalent of 33,300 full-time general practitioners in the country. And by 2020, more than 12,000 additional GPs will be needed in England, according to an analysis by Imperial College London.

The government aims to recruit 5,000 GPs over the next two years — including 2,000 from overseas. But only 38 non-U.K. nationals signed up during the first six months of 2017, according to figures published in The BMJ, a medical journal.

It’s not only doctors that are in short supply across the NHS. The Royal College of Nursing has estimated that there are around 40,000 unfilled nursing positions in England alone.

It wasn't supposed to be like this. In the lead-up to the referendum, campaigners for leaving the E.U. insisted that Brexit would benefit the NHS — to the tune of £350 million ($473.7 million) a week.

The promise was even plastered on the side of the "Leave" campaign’s red bus that toured the country.

The "Leave" campaign's bus advertisements promoted their claim that the NHS would save £350 million a week by leaving the E.U. Jack Taylor / Getty Images

Reality, though, has proven less lucrative: The Financial Times newspaper estimated that the vote to leave has now cost the U.K. around £350 million a week.

During the Brexit campaign, Europeans were frequently accused of overburdening the health service as patients, with the Conservative government even introducing a new policy to crack down on so-called health tourism that it claimed could recoup up to £500 million ($676 million). The British Medical Association described that figure as "exaggerated" and "unreliable."

While workforce pressures may be the highest-profile health sector consequence of Brexit, it’s not the only one.

Research, regulation, medicines, medical devices and reciprocal health care agreements are all areas where U.K. and E.U. organizations and institutions not only collaborate but depend on each other.

A doctor at a hospital in Birmingham, England. Christopher Furlong / Getty Images

“Being part of these networks is in everyone’s interest," said Niall Dickson, chief executive of the NHS Confederation, a membership body of health and care organizations. "There is real concern within the top U.K. universities, academic institutions and hospitals that we continue to be a welcoming place.”

"Whatever immigration policy the U.K. develops," he added, "it should be encouraging these people to come, and U.K. researchers to go and work in Europe."

Analysts think that the challenges facing the health service can be solved if there’s the political will. But given the ups and downs of the Brexit negotiations, anything is possible.

“Nobody yet seems to have a clear idea of where we want to end up,” said Mark Dayan, a Brexit specialist at the Nuffield Trust, an independent health research and policy organization. “It’s not yet clear what the system we are aiming for is, or how we get there.”