Anthony Joshua made it three boxing golds for Britain at London 2012 with a dramatic win over Roberto Cammarelle in Sunday's super-heavyweight final.
Joshua, 22, was unlucky to be trailing by three points going into the final round against the defending champion.
But needing a grandstand finish, Joshua came on strong down the stretch.
The judges scored the fight 18-18 with Joshua winning on countback. The Italians appealed against the decision but were ultimately unsuccessful.
"There are no easy fights in these Olympics," said the Briton. "I have pulled it out of the bag and my heart is pumping with adrenaline.
"The third round is always a good round for me. Again and again, the crowd have come out."
He added: "That medal represents my journey and the support from my team. It is much more than a gold medal, it is a life experience."
Joshua's display puts a golden cap on Britain's best performance in an Olympic boxing tournament since 1920. Britain won six medals at the Antwerp Games but only two of them were gold.
Great Britain also won five medals in 1956, but the tally in Melbourne was two golds, one silver and two bronzes. Dick McTaggart, who claimed lightweight gold in 1956, was in the ExCeL audience to witness Joshua's feat.
Also in the crowd were former Olympic super-heavyweight champions Audley Harrison and Lennox Lewis, although Lewis won his gold for Canada, as well as Wladimir Klitschko, who claimed the super-heavyweight title for Ukraine in 1996.
Joshua got his jab working early and also landed with some sniping left hooks in the opening round, but undid much of his good work by getting caught in the corner in the final seconds, allowing the Italian to nick it 6-5.
Joshua was still landing with ramrod jabs in the second and stiffened his veteran rival with a juddering left hook, but the awkward Cammarelle was landing with shots of his own and took the round 7-5.
With Joshua chasing the fight, it looked like Cammarelle might make the most of his openings in the final three minutes, but Joshua could not miss in the last two-thirds of the round, as the ExCeL crowd lost all inhibitions.
Joshua's rise is an extraordinary tale. He has been boxing for four years and only took up the sport after being dragged to a gym by his cousin.
Joshua was scheduled to fight Cammarelle in a tournament in early 2011, but was told afterwards by his trainers he would have been pulled had the meeting panned out, owing to his relative inexperience.
Eight months later, Joshua beat the 32-year-old Italian police officer at the World Championships in Baku before securing silver.