He became a household name in 1955, with the ITV quiz show, Double Your Money (which had actually originated some years earlier on Radio Luxembourg), and went on to host the long-running talent show, Opportunity Knocks, which began the careers of Les Dawson, Lena Zavaroni and Mary Hopkin, among others. Green was often mocked for his permanent door-to-door salesman's smile and "sincere" manner.
After his death, it was medically proven that Green had been the natural father of Paula Yates, a rumour she had denied when the tabloids first printed the story.