“We didn’t think it could last,” says 87-year-old Ethel Armstrong. “It was just a different world. It was unbelievable that it could be sustained.

“I was from the era that you were responsible for your own health care. There were two systems – if you were ill and your family could pay for a doctor then you were well looked after. If you didn’t have money then you didn’t get a doctor."

She added: "I met one of the babies born on the first day of the NHS. She was so thankful it hadn't been the day before because her mother couldn't have afforded a midwife.

"Before that some women had to choose between getting a midwife and feeding their other children that week."

Mrs Armstrong, from Lanchester, stills works for the NHS, 70 years after she started as a cadet nurse on the day it was established.

The former radiologist, who retired in 1990 after around four decades working in hospitals all over the country, is now a governor at County Durham and Darlington NHS Trust and also volunteers for the NHS Retirement Fellowship and is the only person to have worked for the NHS for its entirety.

As a schoolgirl at Alderman Wood grammar school, in Stanley, she had hopes of studying dentistry or medicine, and with good grades was told she could get a place to do either.

"But my parents couldn't afford to send me there for six years," Mrs Armstrong said. "My tutor told me about a new scheme that was coming in for free health care. I thought he was joking."

Aged 17, she set stepped into a hospital for the very first time. The following year, on 5th July, 1948, she started working as a nurse cadet at St Nicholas Hospital, in Gosforth, Newcastle.

After training at hospitals in Newcastle, she worked all over the country, mainly in radiography and radiotherapy roles.

Recalling her early days, she added: "Protocol, code of conduct, dress code. Those were the things we learned.

"When I finished training I asked what the best advice was. It was to make sure your consultant's coat is clean and well aired, he has a pen in his pocket and his sleeves are unstarched.

"I thought, three years and that's the best advice? But it was true, if you had that right then you had a happy day. It was very much a hierarchy. One of my jobs was to squeeze orange juice and cut cheese into cubes."

Her career took her all over the country. She fondly remembers the birth of the Walton sextuplets in Liverpool, in 1983, where she was working at the time, and the roll out of a breast screening programme, which she was instrumental in.

She said: "If you were to ask what my proudest moment is, it was that.

"We were given the task of getting data from well women to see if we could scan them, do a history and examination. In 1978 we bought an old container for a fiver to put the scanner in and took it around companies.

"We scanned 10,000 women in that cart and because of that they got the Merseyside breast cancer battle bus."

Five days after retiring in 1990, she went to a meeting of the NHS Retirement Fellowship at the former Dryburn Hospital, on the site of the current University Hospital of North Durham (UHND) and soon became a volunteer, a role she has maintained for the last 28 years.

Despite having suffered a stroke and a heart attack, she has travelled more than 42,000 miles in the last three years to visit hospitals around the country – a dedication which earned an MBE earlier this year.

"There's an army of people who are all little cogs in a big wheel," she said. "I never walk through these doors without a thought for the people who sweep the floors or the volunteers. Without them the NHS would be lost."

She added: "It’s not just about doctors and nurses, it’s about the people who cook all the meals that nourish and the radiotherapists and occupational therapists and the volunteers.

"It’s a whole team that works together to care for patients.

"The NHS is full of remarkable people and they all contribute to what Joe Public takes for granted – that the NHS will be there to solve all their problems.

"That’s why I still work as hard as I do – to preserve what we take for granted. Every day I thank God that we've still got a NHS which is free care for all."

  • To find out more about the NHS Retirement Fellowship, which is open to anyone who worked in the NHS regardless of role, visit www.nhsrf.org.uk