Jamaica's Usain Bolt added the 200m crown to his Olympic 100m title in an incredible new world record time of 19.30 seconds in Beijing.The 21-year-old, who won the 100m title in a world record of 9.69 secs, powered past the field to cross the line and smash Michael Johnson's mark of 19.32.Churandy Martina of Netherlands Antilles took silver with defending champion American Shawn Crawford third.Great Britain's Christian Malcolm clocked 20.40 secs for sixth place.American Wallace Spearmon had crossed the line in the bronze medal position but was later disqualified for stepping out of his lane.Bolt told the BBC after his sensational win: "It's great. I have a great feeling. "This is a dream come true. You come out every day to be a champion and I'm just happy."When asked if he planned to go all out for Johnson's world record, the 21-year-old said: "I was worried after the semis."But I told everybody I would leave everything on the track and I did just that."I've proved I'm a true champion and that with hard work anything is possible."Bolt had been accused of jogging through the line in his heats but the Jamaican said he would run flat out in the final and he delivered on that promise with interest.He blasted out of the blocks and was already well clear of the field going into the bend at the Bird's Nest stadium.The Olympic 100m champion accelerated away down the straight, gritting his teeth as he chased down gold and the record that Johnson set 12 years ago in Atlanta.Bolt seized both with ease, becoming the first man to secure the prestigious Olympic sprint double since Carl Lewis in 1984.The 6ft 5in sprinter is also the first since compatriot Don Quarrie in 1976 to hold both sprint world records at the same time.Bolt, who will celebrate his 22nd birthday in Beijing on Thursday, could win a third gold medal when he competes in the 4x100m relay.Welshman Christian Malcolm was satisfied with his achievement in reaching the 200m final after finally rediscovering some following after a spate of injuries."I didn't run particularly great," the 29-year-old said. "But I have got to take the good from these championships."I have made the final and I am injury free, so I can move on and build from this."You have got to keep going because he [Bolt] is going to have a bad day some time. He has had a great championships and got it right on the day but I am improving so I am looking forward to next season."Source: BBC