Today, doctors estimate that a transplanted kidney will continue to function for around two decades, but back in 1973 the prognosis was much lower. It was thought that around 30 to 40 percent of transplanted kidneys would last only five years. One woman from the UK is currently living an astonishing 43 years after receiving a kidney, making the organ in effect 100 years old and defying all predictions from doctors.

When Sue Westhead from County Durham was 25 years old, she was diagnosed with kidney disease. As she recounted to the BBC, she could “hardly walk” and was “a different color,” and she was told that she only had one-tenth of the normal renal function in her kidneys. Her only chance of survival was with a kidney transplant from her mother, Ann Metcalfe, who was 57 at the time, and who “literally gave me life because I wouldn't have lived much longer,” Westhead told the BBC.

Now over four decades on, Westhead is herself 68 years old and going strong with the same kidney donated by her mother all those years ago. That in effect makes the organ an incredible 100 years old, and in November will clock up another year, though obviously individual cells have been regenerating themselves over that period. Westhead is now thought to have one of the world’s oldest successfully transplanted kidneys, far outlasting the modern-day estimate of 20 years.

Kidney transplants are the most common form of transplantation performed today, with nine out of 10 patients on the transplant list waiting for the organs. Even though an estimated 3,000 of the operations are carried out each year, it is thought that most people will wait on average three to four years before one becomes available, as in the UK around 53,000 people are treated annually for kidney failure.

Back in 1973, and the survival rate was nowhere near what it is today. “I remember thinking if I get five years I'll be happy,” says Westhead. “That was 43 years ago and my kidney is heading for 101 years old in November. You just have to get on with life, not play the victim and wrap yourself in cotton wool.” Every day Westhead has been taking 20 pills to make sure the organ is not rejected, while also looking after her health in general.

Her full story is being told on Wednesday, August 10, on the BBC.