Surgeons have performed the first kidney swap between two couples, transplanting the organs into living people who did not know each other.

Roma Horrell, 57, from Cambridgeshire, and a man from Lothian, Scotland, received kidneys from each other's partners in the first paired kidney swap.

Their own partners had hoped to donate their kidneys but were not a suitable match.

Mrs Horrell received a kidney from the Scotsman's wife at Addenbrooke's Hospital in Cambridge on 4 July.

A few hours later, the Scottish man had surgery at Edinburgh Royal Infirmary and was given a kidney from Mrs Horrell's 55-year-old husband, Peter.

The Scottish couple have declined to be named.

Previously, living donor transplants had occurred only between blood relatives or people with a close emotional relationship, such as couples living together. But a change in the rules last year led the Human Tissue Authority to allow strangers to donate to each other.

The new "swap" transplants will usually be of kidneys, because it is difficult and, in many cases, impossible, to use other types of organs without harming the live donor.