Four decades ago, humans achieved something previously thought impossible in a feat that would change lives around the world.
The first successful heart transplant, which took place at Cambridge's Papworth Hospital, was lauded as a success.
The patient, Keith Castle, who was 52 at the time of surgery, went on to live for a further five years.
Although others patients had come before him, none had survived and been discharged from hospital after having the procedure.
Forty years on from the operation which changed medical history, the surgeon and the patient's son have met to share memories of that history-making day.
Mr Castle's son, also Keith, told of the family's awareness that the operation was his father's last chance to live.
He said: "My father was of the mind that he was determined he would take it."
For the surgeon behind the procedure, who had overcome fierce resistance from within the medical fraternity, the operation's success was vindication.
His name was Sir Terence English.
The pioneer told ITV News: "I believed it would have a future.
"What I didn't realise at the time, and there wasn't data, was how long our patients might well live for."
From one operation, thousands of lives changed
Since the first pioneering operation, more than 8,000 heart transplant patients have been given the gift of life.
Now competing in the Transplant Games in Newcastle, Louise McLellan is one of the lucky ones.
On the 40-year anniversary, she said: "Seven years ago I didn't think I'd be alive.
"To be able to show the world what organ transplants can do, for me that's what it's about."
Richard Worthington had a transplant by the same doctor who carried out the first operation, some 35 years ago.
He told ITV News: "I'm very lucky.
"I can continue working, I married a nurse, I have four wonderful children, and I'm loved.
"That's great for me."
The NHS says survival rates are stronger than previously, with half of all patients expected to live for more than a decade after their operation.