South Asian doctors were the "lifeblood" of the NHS in its early years and prevented a recruitment crisis, a historian has said.
Dr Julian Simpson, author of Migrant Architects Of The NHS, said around 16% of GPs working in the health service at the end of the 1980s were born in India, Pakistan, Bangladesh or Sri Lanka.
The role of doctors from the Indian subcontinent between the 1940s and 1980s is explored in a new exhibition based on the book at the Royal College of General Practitioners (RCGP) in London, ahead of the 70th anniversary of the NHS.
South Asian doctors faced "huge obstacles" after coming to the UK, with the British medical establishment "profoundly racist at the time", Dr Simpson said.
Some job adverts were marked for "British graduates" and many migrant doctors were forced into general practice in the most deprived areas of the country, roles considered less desirable by home-trained medics.
Dr Simpson said: "By becoming family doctors, South Asian doctors prevented a GP recruitment crisis.
"Through their work, they shaped the field as it transformed itself into the cornerstone of the British healthcare system.
"It's important to also remember that the NHS was established to make healthcare accessible to those who could not afford it.
"And for millions of people, particularly in working-class communities across Britain, accessing that care meant going to see a GP from the Indian subcontinent.
"Doctors from the Indian subcontinent were therefore not just contributing to the NHS, they were its very lifeblood."
Professor Mayur Lakhani, president of the RCGP, said: "General practice in the UK would not be what it is today without the hard work, innovation, and courage of our predecessors, and their dedication to delivering high-quality patient care.
"Indeed, without them, our profession and the NHS might not even exist at all.
"Not only were they doctors, but they became highly-valued members of the communities in which they practised."
Dr Simpson added: "It's an important history that is central to the NHS and the NHS can't develop in the way it develops at the time without this.
"But I think it's also in some respects a difficult history, and certainly people had difficult experiences."