LONDON (NYTIMES) - Tanja Pardela is leaving London. Her last day is Sunday. She wells up talking about it. She will miss jacket potatoes, and Sunday roasts, and her morning commute - past playing fields, small children in school uniforms and a red telephone box - to the hospital where she has been a pediatric nurse for 11 years.

Pardela does not want to leave the country she came to more than a decade ago. But that country no longer exists. On June 24 last year, she said, "We all woke up in a different country."

Seventeen months after Britain voted to leave the European Union, many Europeans are voting to leave Britain - with their feet. Some 122,000 of them packed their bags in the year through March, according to the latest figures available, while the stream of new arrivals has slowed.

In London, a city long sustained by European bankers, builders and baristas - "a place that makes you dream," Pardela said - the departures are beginning to hurt. Construction companies and coffee shops are struggling to recruit. Top universities worry about retaining talent. And nowhere are the concerns more elemental than in Britain's treasured and already overstretched National Health Service.

Long before Brexit, the NHS suffered from chronic staffing shortages, and today the country has 40,000 nursing vacancies. But recruiting nurses from the European Union had helped plug the gap - especially in London, where the share of nurses from the Continent is about 14 percent, or twice the national average. King's College Hospital, the massive institution where Pardela works, is short 528 nurses and midwives, and 318 doctors.

Brexit seems certain to make it harder and costlier to recruit from the Continent, assuming that people will still want to come from there. Even the legal status of European Union citizens already living in Britain remains unclear, entangled in the stalled Brexit talks between Brussels and London. Many fear they could lose rights, job security, pensions and access to free health care.

This uncertainty is one reason that some European health care professionals are either leaving or thinking about leaving. In the year following the referendum, almost 10,000 quit the NHS. The number of nurses from other European Union countries registering to practice in Britain has dropped by almost 90 per cent.

As yet, there is no mass exodus back to the Continent - the number of European Union staff in the health service even grew slightly in the year after the referendum. But the trends are unmistakable: The number of Europeans leaving the system is rising, and the number joining it is falling.

"With London in the grip of its worst-ever staffing crisis, nurses are being pushed to breaking point on understaffed wards," said Tom Colclough, regional spokesman for the Royal College of Nursing in London. "If those EU colleagues who have not yet left are not given an unequivocal right to remain, the very safety of the capital's care settings will be under threat."

The NHS, with its philosophy of free universal health care, is a pillar of postwar British identity, once described by a former minister as the closest thing the English had to a national religion. When London hosted the 2012 Olympics, a highlight of the opening ceremony was a dance performance by real nurses whose bodies eventually coalesced into three giant letters: NHS.

During the Brexit campaign, an argument about the NHS helped tip a tight vote. Brexit advocates said leaving the European Union would allow the government to repatriate £350 million (S$628 million) a week from Brussels and spend it on health care. It was a powerful promise, plastered in bold across the side of a campaign bus - but it was false: Britain pays only about 166 million pounds a week net into the European budget, and there was little chance that even a lesser amount would go solely to the NHS.

"It was clearly the most effective argument not only with the crucial swing fifth but with almost every demographic," the chief strategist of Vote Leave, Dominic Cummings, wrote in The Spectator this year. "Would we have won without immigration? No. Would we have won without £350m/NHS? All our research and the close result strongly suggests No." Founded in 1840, King's treated shell shock victims during World War I and victims of German air raids during World War II. More recently, survivors of London's terror attacks and the Grenfell Tower fire were treated here.

The hospital is a complex of two dozen buildings in southeast London with Europe coursing through its circulatory system. Dutch workers built the state-of-the-art helipad on the roof. Eastern Europeans are helping to build a new intensive care wing and serving cappuccino as baristas in the four coffee shops. Of the 9,300 clinical staff, 1 in 7 holds a non-British European passport.

Brexit is forcing a stark reassessment in every department. In the emergency room, Cyril Noël, a French doctor, is wrestling with how a country he loved rejected him. He describes the grieving process as the Five Stages of Brexit. In critical care, Georg Auzinger, an Austrian physician, has built a world-class facility but now worries about finding enough doctors and nurses.

Many worry that a health service they cherish may be existentially at risk. During a recent Sunday service in the hospital chapel, the priest said a prayer to guard against the "effects of Brexit." "The NHS is in Britain's DNA," said Shelley Dolan, chief nurse and executive director of midwifery at King's. "Europe is in the DNA of the NHS."

The Five Stages of Brexit

When Noël, the French emergency doctor, started his shift early one recent afternoon, the department was already two dozen beds short. He surveyed the scene: seven stroke patients, two casualties from traffic accidents and a couple of stabbing victims. An elderly lady had been run over by her own car after forgetting to put on the hand brake. A toddler had swallowed a refrigerator magnet. A man had almost died after being punched in the face.

And the emergency room was four nurses down.

"Just a regular Friday," said Noël, 45, as someone behind him mopped up the blood stains in Bay 4.

Working with Noël that Friday night were a Czech doctor and nurses from Ireland, Poland, Spain and Portugal. Several had spent their summer vacations scouting job opportunities in their home countries. "Everyone is nervous," said Alexandra Cunderlikova, a senior nurse from Slovakia.

Cunderlikova came to Britain in 2003, a year before her country joined the European Union. She remembers lining up outside the Home Office at 4 a.m. for her work visa.

"I wonder," she said. "Will it go back to that?" There are still more Europeans migrating into Britain than leaving. But, as in the NHS, arrivals are slowing and departures accelerating, said Madeleine Sumption, director of the Migration Observatory at the University of Oxford, especially among Eastern Europeans like Cunderlikova.

The day before the Brexit referendum, feeling anxious and powerless because he was not allowed to vote, Noël did something he had never done before: He placed a bet.

Noël wagered £200 on Brexit. "That way, I thought, if it actually happens, at least there is one positive thing in it," he said. To his dismay, he won. The £1,500 he made would roughly cover the fee for a British passport. But Noël is in no mood to become British - at least not now.

"I feel very strongly European," he said.

Noël grew up as an Anglophile in eastern France, near the German border, in a family badly scarred by two world wars. When he was 5, he paraded across the local market, pretending to speak English. At 30, he fell in love with a British student who had come to France on the Erasmus program, the European Union's university exchange scheme. Twelve years ago, they moved to Britain and Noël instantly felt "at home." But now, when he works outside London in places where people voted for Brexit, resentment rises in his throat.

"I've had very torn feelings about helping people who expressed the wish to get rid of us," Noël said.

"Psychologically Brexit has had a huge impact," he said. "You feel rejected as a group." He talks about the "five stages of Brexit." First there was shock, he said. Then there was denial. ("Don't worry," he would tell the young nurses from Portugal and Spain in his department who fretted in the months after the vote. "Nothing is going to change.") Eventually, Noël reached the anger stage, following a cascade of nasty news reports: about a government request for companies to compile lists of foreign nationals (later retracted); about a man being stabbed for speaking Polish; about a Finnish professor who, along with scores of other Europeans, was served a deportation notice.

The notice was a bureaucratic mistake. "But after Brexit, such mistakes are not easily forgotten," Noël said.

If the NHS has consistently managed to produce health outcomes comparable to countries with vastly more resources - like France, which has a similar population but more than twice the number of hospital beds - it is in large part because of the people, said Noël, who has worked in both systems.

"The NHS is an incredibly resilient system," he said. "People are so dedicated. When the system is squeezed, they work even harder." But Brexit has made many European employees reconsider. If anger was the third stage of Brexit, and depression was the fourth, Noël said he had now reached the final stage, acceptance.

For him, that means leaving Britain early next year. He has a new job at a hospital in Dubai.

Replacing One Immigrant Group With Another

Up two floors from the emergency room, down a warren of hallways and through a pair of locked wing doors is the liver intensive care unit.

Auzinger, the clinical head of critical care, was checking on two patients who were recovering from emergency liver transplants on extracorporeal membrane oxygenation, a pioneering bypass technology. Their blood, liters of it, was being drained from their bodies, oxygenized in an external pump and then reintroduced. Anywhere else in the world they would have been kicked off the transplant list and have died.

The liver department at King's is world famous. It is also very European. "The English are in the minority," Auzinger said.

Auzinger, a lanky 51-year-old from Salzburg, Austria, has a clipped accent and speaks in Briticisms ("I was gobsmacked," he says of the Brexit result). The liver department's clinical director is Irish. Its academic director is Spanish. The hospital recently tried to hire a German as academic head of department, but he declined: He had been awarded a high-value European grant that he could not take to Britain after Brexit.

This worries Auzinger, who has to hire 407 nurses and doctors for the hospital's new intensive care wing. Last month, not a single European applied for an advertised position as a senior consultant. "Before, at least a third of applicants were European," he said.

Auzinger is happy to hire qualified Britons. "But there are not enough doctors and nurses in this country," he said. "The numbers being trained do not cover the needs." In March, the government announced a plan to hurriedly train more British nurses. Yet in September, enrollment at nursing schools dropped because the government also cut grants to nursing students. That is one reason Peter Absalom, associate director for recruitment at King's, is now trying to replace one immigrant group with another. "We are looking to the Philippines, Australia and India," he said. Three major recruitment drives are planned over the next 12 months.

Every time Absalom hires workers from overseas he has to pay for their visas and a collection of other charges, which add up to more than 4,000 pounds per person over three years. It can take a year before the nurses start work. Europeans could be hired with no visa costs and no extra paperwork. Over the past five years, nurses from Portugal, Spain, Ireland and other European Union countries have accounted for about a third of the total intake.

Now King's has stopped its hiring campaigns in the European Union.

"What is particularly difficult is that we cannot give candidates any certainty on their future status," Absalom said.

Auzinger has been in London for 18 years. He, too, would consider going back to Austria if he could transplant his job there, but he cannot. He thinks the way Brexit is affecting the NHS is symptomatic of a poor treatment plan. Britain is ailing. People are angry. Brexit was the treatment offered to them. What worries Auzinger is the lack of a diagnosis.

"If you think Brexit is the medicine, my concern is that you're treating something blindly," he said. "If you don't have a diagnosis, you cannot treat the patient properly."

'Why Am I Still Doing This Here?'

Pardela, the pediatric nurse, still needs to stop by the post office so that her mail can be forwarded to Germany. She is keeping her British bank account because she hopes that one day the pound will rise again. It has lost as much as 20 percent of its value against the euro since the referendum. So have her savings.

After the Brexit vote, a British colleague urged Pardela to apply for citizenship. Her skills were needed. No way, she answered. "I respect the vote," she had said. "But I'm not going to bend to it." Last September, she called an old friend from nursing school and asked about job opportunities back in Germany.

"Brexit was a trigger," said Pardela. "It makes you reassess your life. You find yourself thinking: 'I'm working really hard. I haven't had a pay raise in four years. Now they're telling me they don't want immigrants? Why am I still doing this here?'"

"And then you think: 'I'm 45. I better move now. It will be harder when I'm 55.'" In her small apartment, filled with moving boxes, Pardela was packing photos of Big Ben and the London Eye, as well as a series of trashy romance novels that helped her learn English. Still on the refrigerator was a magnet featuring Florence Nightingale, the mother of modern nursing in Britain: an Englishwoman who was born in Italy and trained in Germany.

One reason Pardela thinks the NHS is one of the best health care systems in the world is that it empowers nurses. "The range of opportunities and responsibilities is much greater here," she said. In Germany, many of the things she has been doing - assessing blood results, adjusting treatment plans for transplant patients - would be handled by a doctor.

On Pardela's ward, a third of the doctors are European. Twice a year they hold an International Food Day where people contribute dishes from their countries. This year, Pardela brought sausage and sauerkraut. A Greek colleague made tzatziki. An Italian cooked spaghetti.

When the latest bout of cost savings required the department to cut one nurse from every shift, Pardela fought hard to win the role back. It took a year. In the end, she was successful.

"The irony," she said, "is that now we can't find anyone to fill it." The position has been empty since September.