Sir Cliff Richard has revealed he has been treated for prostate cancer for the past year.The 85-year-old singer said his cancer had “gone at the moment” and backed calls for a national screening test for men.In an interview with Good Morning Britain, he said: “I don’t know whether it’s going to come back. We can’t tell those sort of things but we need to, absolutely, I’m convinced, get there, get tested, get checked.