But heart surgery still carried a lot of risks, which frustrated Mr Watson, especially following the death of a young patient after a long operation. In 1967, this pushed him to found what was then the National Heart Research Fund with the aim of making surgery safer.

He launched an appeal with the Yorkshire Evening Post to raise funds to research ways of improving the safety at a time when 70 percent of heart attacks ended in death.

“So I decided to found a new charity, specifically to try and reduce this risk of heart surgery. Now, of course, from a small beginning it has grown considerably and I’m very proud that at the present time they contribute something like over £2 million a year to research, development, education and treatment of heart disease,” Mr Watson says.

In 1976, he developed an artificial heart valve which became the prototype for those used in heart surgery today. It was one of the most durable and reliable valves created and was used for 30 years.

Then in 1979 Heart Research UK funded six of the first eight successful UK heart transplants, carried out by Sir Terence English at Papworth Hospital, breaking the moratorium on UK heart transplants after being deemed too dangerous in the late 1960s.

“I supported his programme at a time when he couldn’t get funding from either the NHS or the British Heart Foundation. It was our support that enabled him to proceed,” Mr Watson says.