An Oxford doctor has been recognised for his work that showed the clear link between smoking and cancer.
Professor Sir Richard Peto showed that people who gave up could expect an extra 10 years of "good healthy life."
His findings have led to a significant drop in smoking-related deaths.
As a result he was given a lifetime achievement award by the British Medical Journal (BMJ), at a ceremony on Wednesday.
Another doctor, Sir Richard Doll, began working on the topic 60 years ago and brought Professor Sir Richard Peto to Oxford to help.
As well as highlighting the dangers of smoking, they showed that other cancer-causing factors were significantly less important.
He said: "If you add up all the other reliably known causes of cancer in this country they'd add up to less than half of what smoking does.
"In the 1970s we had the worst death rate in the world from smoking.
"The overall death-rate has gone down and the main reason for that is people have stopped."
While he is happy to see the benefits of his work, he is not complacent about the continuing problems caused by smoking.
He said: "There are a million deaths from smoking in China and things are getting worse rather than better.
"There is another million in India so we have 100 million deaths from smoking in the 20th century and we are going to have a billion deaths from smoking this century if people carry on the way they are."
He added: "If they stop we'll all be out of work, it'll be lovely."