Luke Campbell made it two golds for Great Britain in the boxing ring with victory over Ireland's John Joe Nevin in the bantamweight final.
Campbell, 24, took a tense opening round 5-3 before Nevin looked like he might turn things around in the second, which he nicked 5-4.
But with the Irishman chasing, Campbell floored his rival in the third on the way to a deserved 14-11 win.
"It's a day I've dreamed of for a long, long time," said Campbell.
"I'm lost for words. It means everything. My family, my city, everyone has been so supportive.
"A lot of my family and friends have seen how disciplined I've been and they are just so proud of me. I'm happy I could make them proud of me."
Super-heavyweight Anthony Joshua and welterweight Fred Evans can boost GB's medal tally when they fight for gold on Sunday.
Nicola Adams has already won women's flyweight gold for Team GB, while middleweight Anthony Ogogo took bronze on Friday.
The bout between Campbell and Nevin, 23, was a decider. Hull southpaw Campbell beat Nevin on countback in the semi-finals of last year's world championships, while Nevin won 13-2 at the EU Championships in 2009.
The opening couple of minutes were a cagey affair, although Campbell, happy to bide his time and let Nevin make the first move, landed with the sharper punches.
But Nevin was undeterred and took the second round courtesy of some solid shots, including a juddering right hand shortly before the bell.
The man from Mullingar, County Westmeath, was still chasing a lead in the final round. Campbell retained his focus, kept his shape and dropped Nevin with a short left hand on the way to a three-point victory.
On having his arm raised, the product of St Paul's Amateur Boxing Club dissolved into tears, a sign of how much the gold medal meant to him.
It is the best performance by a British boxing team at an Olympics since Melbourne 1956, when two golds, a silver and two bronzes were won.
Ireland finish the tournament with one gold, one silver and two bronzes. Four of their five medals at London 2012 have come in the ring.