I've watched people having their chemo stopped and their heart surgery refused – this is the reality of the NHS's stance on immigration

These cases are particularly devastating for us to work with, because they are preventable

As the NHS turns 70 this week there is much to be proud of, and much to fight for. I started working as a doctor in the NHS in 2009 and even in that short time it has changed profoundly, and not always for the better.

In January 2017, the practice of sharing patient information began. NHS Digital entered a deal with the Home Office which allowed immigration officials to request patients’ personal information, including their last known address and date of birth, without their consent and their GP’s knowledge. The deal meant many patients were too scared to access healthcare due to fear of arrest, detention and potential deportation.

We saw the impact of the fear this deal created every day in our Doctors of the World (DOTW) UK clinic, where we treat patients who are struggling to access healthcare through no fault of their own. We see pregnant women too scared to give their address or attend antenatal care, increasing the risk of complications for them and their baby. One woman came to our clinic in labour because she was too afraid to go to hospital. These cases are particularly devastating for us to work with because they are preventable. Years of progress in maternal health care is being undone by denying access to those who need it.

A group of organisations stood up to this draconian policy through our #StopSharing campaign, and by giving evidence to the cross party Health and Social Care Committee. We also welcomed committee MPs Paul Williams and Luciana Berger to our clinic to listen to patients who were too scared to see their GP. Thankfully, this agreement that violated patient confidentiality and the doctor-patient relationship has now been amended. We eagerly await the new terms.

Despite this success, many challenges remain. The government’s “hostile environment” continues to weaponise healthcare, putting both individual and public health at risk. In October 2017, upfront charging was introduced for those unable to prove they are entitled to NHS care. With a few exceptions, if a patient cannot pay up front, they are refused care. As a health advisor, I have seen the devastating impact this has on people. I have seen people refused heart surgery, denied cancer treatment or have their chemotherapy stopped.

One patient left in this terrifying position was Djibril, who arrived in the UK 17 years earlier, fleeing political persecution in his home country. Even though his asylum claim was refused, his country of origin would not issue papers to enable him to return, leaving him stuck in limbo. He was diagnosed with cancer in 2016 and told he needed surgery, but the operation was cancelled because of his immigration status.

Djibril’s medical notes explained that there was a risk of the cancer spreading if he did not receive treatment, yet his surgery was deemed “non-urgent” and was withheld unless he paid a huge sum in advance. He said he was “very scared and desperate” and he worried that his “days were numbered”. With our help and a lawyer, the treatment was finally provided.

It shouldn’t be this way. Denying people healthcare is inhumane, costs the NHS far more in the long run and puts doctors in an impossible position. Doctors want to treat the patient in front of them – they must be allowed to do their job.

On July 5 1948 the NHS was founded on three principles: that it meet the needs of everyone, that it be free at the point of delivery and that it be based on clinical need, not ability to pay.

It is these principles that make it an honour and a privilege to be one of the 1.5 million people in the UK who work to keep the NHS going every hour of every day. These principles top the list of things that make people most proud to be British, and keep the UK at the top of the global list of health system performance scores, despite funding failing to keep pace with demand. And it is these principles we must fight to restore.

Lucinda Hiam is a health advisor at Doctors of the World (DOTW) UK