Marianne was expecting the phone call to be quick. She had just moved house and what she needed was for her new doctor to issue the medications she usually received from her old doctor. But as she stood in her hallway, surrounded by boxes, the writer and mother of two felt the stress inflating inside her as she realized this was not going to be easy. Marianne, speaking using a pseudonym to keep her medical details private, had only traveled 200 miles (300 kilometers) from southern England to the Midlands, but it felt like she’d moved to a different country.

This new doctor knew nothing about her—her multiple chronic conditions, or the list of around 20 medications she needed to manage them—and asked her to detail her entire medical history on the spot, and to list the names and dosages of drugs she’d been prescribed over the years.

In theory, patients in the UK’s free-to-use National Health Service (NHS) should be able to transfer their data when they change doctors. But in practice it doesn’t always work. “It was me that had to do all the running around,” says Marianne. In the end, it took her an entire month to get the details of her own prescriptions.

The vast majority of people in the UK use the NHS for medical treatment. Every day that means around 1.3 million appointments with doctors, 260,000 hospital appointments, and around 675 people entering serious, critical care. Each of those interactions creates new records in the system. But that system is made up of tightly controlled silos. Health care staff can’t easily access information about their patients from different parts of the service, even if those patients ask them to. For years, the NHS has tried to build a computer system to manage the vast amount of data it generates. So far, it’s failed, most recently due to public uproar over privacy. Now it’s trying again, issuing a contract to build a central operating system that will allow anonymous patient data to move more freely around the service—between different departments in one hospital, from hospitals to the social care system, and in some cases from general practitioners' offices to local authorities.

The NHS argues that this new system—officially known as the federated data platform—will improve care for patients. “A federated data platform will connect data and improve decisionmaking by bringing different systems together in one secure environment,” says NHS England chief data and analytics officer Ming Tang. The health service has previously said the contract winner would be announced by the end of September.

The idea isn’t controversial. However, the front-runner in the bidding to build the system is. Doctors, privacy campaigners, academics, and politicians from the ruling Conservative Party have expressed concern about the favorite to win the £480 million ($595 million) contract, the US tech company Palantir. Palantir’s cofounder is Peter Thiel, a prominent donor to former US president Donald Trump’s political campaigns. One of its early backers was the investment arm of the CIA. Its technology has allegedly been used to detain migrants in the US and direct drone strikes in Afghanistan. With that heritage, they wonder, can Palantir really be trusted with the NHS’s data?

“We just think Palantir is a completely inappropriate partner,” says Hope Worsdale, a spokesperson for Just Treatment, which campaigns against privatization in the health service. “We think those things Palantir was involved with are counter to the values that underpin the NHS.”

Palantir declined to comment on the procurement process, but Tom McArdle, a health care deployment strategist at the company, said it was proud of its record working with the NHS. “Our software powered the vaccine rollout and ensured ventilators were sent where they were needed most,” he says, adding that 36 branches of the NHS are already using Palantir’s software.

Britain regards its health service with reverence, demonstrated during the pandemic when people all around the country took to standing outside their homes every Thursday evening to clap for the NHS in a ritual gesture of appreciation to the service and its staff.

But the NHS is creaking, under pressure to care for an aging population on overstretched budgets. Many doctors and nurses have spent the summer intermittently on strike, while waiting lists for treatments stretch ever longer. As the service looks for cost-saving “efficiencies,” the public worries that privatization is coming, and with it, an American-style system of costly insurance that takes basic health care out of the reach of millions. Polls show that the British public is not totally against private companies working within the NHS system—60 percent believe there is a role for them if they do not push up costs. But only 2 percent of people favor total privatization.

The service does have one asset of immense value to the private sector—the data it has on the British population. That data is so unique, consultancy Ernst and Young has valued it at £9.6 billion ($11.9 billion) a year. “Especially for things like AI and things like the life sciences, it's one of the most valuable data assets in the world,” says Joe Zhang, a health data scientist and clinical research fellow at Imperial College London.

Giving a private company access to that data could, some critics of the contract say, be a forerunner of more substantial privatization, and a step toward a future for the NHS that many in the UK say is not what they want.

“Palantir is not only the emblem of what privatization in the NHS might look like,” says Jeni Tennison, executive director at Connected by Data, a group that campaigns for individual data rights, “but also an emblem of the kind of database state and the growing datafication of our lives and our lack of control over that.”

Palantir's eagerness to court the NHS has become an open secret. “Palantir have been lobbying their way toward this deal for years, and it looks like they’re about to hit pay dirt,” says Cori Crider, director of advocacy group Foxglove, which is running a campaign to keep Palantir out of the NHS. So far, the company’s charm offensive has involved taking NHS executives out for £60 watermelon cocktails and plotting ways to “take down political resistance,” according to emails that were leaked to Bloomberg. Reservations about Palantir were further exacerbated when Peter Thiel, billionaire cofounder and chairman on Palantir’s board, compared Britain’s obsession with the NHS to Stockholm syndrome. That comment seemed to confirm that Thiel was in favor of privatizing the NHS, according to Eerke Boiten, professor of cybersecurity at De Montfort University. “I don't want those people too close to the NHS data,” Boiten says.

These comments were made by Thiel in a private capacity, says Palantir’s McArdle. “Our CEO has made it clear he disagrees with them and that he wishes ‘we had a health care system in the US that served the poor and underserved as well as I perceive the British system does.’”

There is a lot of speculation in the UK about exactly what data Palantir would handle, and how that data would be used.

Zhang says that there are three pools of “de-identified” data—i.e., data that has had patient names and other identifying marks taken out—that could potentially be included in the system.

The first is primary care data. That’s simple to extract; it just sits on, say, your general practitioner’s computer system. The second is hospital data used for payments, which is basically an Excel spreadsheet of every patient who has come in for care and the treatment they received. The third type of data is the hardest to get to, which is the data locked behind individual hospitals’ systems. This type of data is the granular day-by-day data, like the notes that doctors write or clinic letters, and traditionally it’s been tricky to get at, as it’s all locked behind proprietary software. There are 20 to 30 different hospital systems in the NHS, and every one is like a separate company, says Zhang.

The NHS insists that whatever company builds the system, it would be the NHS that decides how data flowing through it is used. “The NHS doesn’t take trust for granted, which is why the successful supplier of the federated data platform will only operate under the instruction of the NHS and will not control the data in the platform, nor will they be permitted to access, use, or share it for their own purposes,” says the NHS’s Tang. “We have also put in place explicit safeguards to prevent any supplier gaining a dominant role in NHS data management.”

Yet that message hasn’t dispelled public fears that this data could be monetized at a later date.

“We would have a concern about any external profit-seeking company being involved in health care,” says David Wrigley, deputy chair of the British Medical Association’s GP committee in England, adding that he would prefer the NHS to build this system itself. “We think health care should be funded by taxation and there should be no profit elements—that would include the usage of data and how patient records are handled.”

Palantir denies allegations that it can’t be trusted to manage NHS data and would monetize it in some way. “What these claims do is fundamentally misunderstand how that software is used,” McArdle says. “Unlike many other technology companies, we’re not in the business of collecting, mining, or selling data. What we do is provide tools that help customers understand and organize the information they hold, along with training and support in using those tools.”

But opposition to Palantir’s role—should it win—isn’t just about the facts of the contract, but the fact there’s a contract at all. Many critics argue the NHS should be developing the teams to do this type of work itself. “There are far fewer digital experts now in the NHS,” says Wrigley. “That's because the government decided to cut back on a lot of funding. It's a sort of self-fulfilling prophecy.”

If Palantir does win the contract, researchers are worried NHS patients may decline to share data with any part of the NHS in protest. The last time the NHS tried to introduce data-sharing for research purposes, more than 1 million people opted out within a month. “What's going to happen here will be hugely damaging to people's trust,” says Barbara Prainsack, a professor at the University of Vienna whose research explores the social, ethical, and regulatory dimensions of data in medicine. Research has found that the public is happy to share data with commercial organizations if the relationship is built on honesty and transparency, and has a clear public benefit. “There wasn't a public debate around this contract, so this gives the impression of secrecy, that there’s something to hide.”

Even after her experience, Marianne has reservations about enlisting Palantir—a company she’s never heard of—to solve the NHS’s data problem. “I think we probably would feel more comfortable if it was just the NHS and not a private company,” she says. “Anyway, I suspect that that ship has sailed.”