Jessica Ennis, Greg Rutherford
and Mo Farah win golds in the Olympic Stadium after earlier British
success in cycling and rowing.
In front of a rapturous crowd that included the Duke and Duchess of Cambridge and David Cameron, Mo Farah crowned Britain's "Super Saturday" by winning the 10,000m.
With two more golds in the rowing and another in cycling, it has been Britain's most successful day at the Olympics for more than 100 years.
Britain now has 29 medals in total - 14 gold, seven silver and eight bronze - and stands third in the overall medal table.
Ennis, who has been the poster girl for London 2012, went into her last event - the 800m - with a huge lead and comfortably won the race and with it the overall contest.
Earlier, the 26-year-old from Sheffield had wowed the capacity crowd by producing 6.48m in the long jump and a lifetime best of 47.49m in the javelin.
After clinching victory, she sank to the floor and wept with joy. "I am so shocked, I can't believe it. I am so happy," she said.
Rutherford, 25, from Milton Keynes, leapt 8.31m to become the first British man to win long jump gold for nearly 50 years and secure the second athletics gold of the night.
The third was only moments away as Somali-born Farah blew away the field to take the 10,000m title. "This is the best moment of my life," he said.
Across the Olympic Park at the velodrome, Laura Trott, Joanna Rowsell and Dani King were triumphant in the women's team pursuit and also smashed the world record.
After their crushing defeat of the US in the final, a jubilant Trott said: "It has been my dream since I was eight - and we have just gone and done it."
Team GB has now won a staggering four of the five gold medals on offer so far in the track cycling, with five events still to come.
At Eton Dorney, it was another glorious day on the water with Britain winning two more golds and narrowly losing a third to take silver.
Katherine Copeland and Sophie Hosking were completely stunned after they won the lightweight women's double sculls at Eton Dorney.
The pair became the third female British crew to take Olympic gold this year after finishing a length and a half ahead of their closest rivals China.
Fighting back the tears, Hosking said: "I can't believe this is real, that we just won. We just won the Olympics!"
Their win came after joy and heartbreak in the men's team as the coxless four won gold but the men's double scullers narrowly failed to defend their Olympic title.
Andrew Triggs Hodge, Pete Reed, Tom James and Alex Gregory led from the front to win the four, which means Britain has now won the event in the last four Olympics.
Reed said: "The hours we do, the pain - it was all worth it in the end."
But in the double sculls, Zac Purchase and Mark Hunter were beaten at the death by Denmark and were distraught at only taking silver.
There had also been disappointment earlier when Britain's Helen Jenkins failed to win a medal in the women's triathlon in Hyde Park. The reigning world champion finished fifth after struggling with injury.
Over at Wimbledon, Andy Murray and Laura Robson guaranteed at least silver by winning a tense mixed doubles semi-final against Australia.
Murray now has two shots at a gold medal on Sunday, when he will also play Roger Federer in the singles final in a repeat of his Wimbledon clash just weeks ago.
However, the British team crashed out of the football after losing the quarter-final to South Korea on penalties.
Elsewhere, history was made when South Africa's Oscar Pistorius became the first double amputee to compete in the Olympics and Paralympics, advancing to the semi-final of the 400m.
The crowd at the Olympic Stadium also had their first glimpse of the world's fastest man, Usain Bolt, who cruised to victory in the men's 100m heats ahead of Sunday's final.
Former world champion Kim Collins missed the 100m qualifying after being dropped by St Kitts and Nevis - allegedly for spending a night in a hotel with his wife and children.
A team spokesman said Collins had broken team rules by leaving the athletes' village at the Olympic Park.
Collins tweeted: "For those who saw me run in Mexico, that’s the last time I represent my country. Even men in prison get their wives to visit."