Karsten Warholm was the breakthrough star of the World Athletics Championships. In London's torrential rain the 21-year-old Norwegian stunned himself and the rest of the world by winning the 400 metres hurdles gold. The former decathlete was propelled into the limelight, with his winning scream expression going viral. But how has life changed for the boy from the small Norweigan harbour town? Sportsworlds Lee James has been to visit him back on the track in Oslo, where he achieved his first major win over the hurdles at the Diamond League meeting at Bislett.