More than 20 people in the UK have donated a kidney to a stranger, according to the Human Tissue Authority.

Andy Loudon, a retired carpenter from Bedfordshire, received a kidney from Plymouth nurse Barbara Ryder in 2007 in what was one of the first of the UK`s altruistic kidney donations.

Figures from the Human Tissue Authority show that 22 transplants have been carried out so far, while 15 people were approved as altruistic kidney donors in 2008-09, an increase on the 10 in 2007-08.

Organ transplants traditionally come from people who have died, but the practice of living donation, from friends, family or partners, to those who are ill is becoming more common. The HTA approved 1,023 living donations in 2008-09.

Currently, there are 6,961 people on the waiting list for a kidney transplant in the UK, while in 2009 a total of 2,298 kidney transplants were carried out.

Director of policy and strategy at the HTA, Vicki Chapman, said: “It is remarkable to see an increase in the number of people who want to donate a kidney to someone they do not know.”