“This is enough for me, this is the perfect end to my Olympic career”
Sir Chris Hoy
There was also gold in the velodrome for Laura Trott in the omnium.
Britain had won gold earlier in the day thanks to triathlete Alistair Brownlee and the dressage team.
Britain have now achieved their best Olympic gold medal haul in 104 years, eclipsing the 19 they won in Beijing.
They have also overtaken the overall medals tally from 2008 with five days of action left, after Robbie Grabarz took bronze in the high jump.
With guaranteed medals to come in the men's and women's boxing events, Britain now have 48, achieving the minimum medals target set by UK Sport, the body that funds the country's Olympians.
"What has been achieved today is the result of a shared commitment made by 541 athletes, representing 26 sports, to compete as One Team GB, and to do so in a manner that would make our country proud," said Team GB chef de mission Andy Hunt.
Sir Chris Hoy claims historic sixth gold
"It is the result of years of sacrifice and struggle, underpinned by the selfless contributions of coaches, team-mates, parents, volunteers, administrators and the British public.
"We congratulate the athletes of Team GB on reaching this remarkable milestone and offer our thanks to everyone who has supported them."
Speaking after his success, Hoy, who now has six golds and one silver from an Olympic career that began in 2000, told BBC Sport: "I'm in shock. You try to compose yourself but it's surreal.
"I wanted to win gold in front of my home crowd. I saw everyone stepping up to the plate and thankfully it worked out for me too.
"I can't describe the feelings I have at the moment. This is enough for me - this is the perfect end to my Olympic career.
Best of British - Most medals
Sir Chris Hoy
- 6 gold, 1 silver
- 4g, 1s, 2b
Sir Steve Redgrave
- 5g, 1b
- 4g, 1s
- 3g, 2s
- 3g, 2b
- 1g, 2s, 2b
Sir Matthew Pinsent
- 3g, 1s
"I can't put into words what it means to me. It's one of the greatest feelings I have ever had."
Rower Redgrave has six Olympic medals - five golds and one bronze - while cyclist Bradley Wiggins, who won the men's road race earlier in the Games, has won seven medals - four gold, one silver and two bronze.
Hoy, who was hugged by Redgrave as he spoke to the media after his win, is 36 and unlikely to compete at the 2016 Games in Rio de Janeiro but could carry on until the 2014 Commonwealth Games, which are being held in Glasgow.
"I'm 99.9% sure I won't be competing in Rio," said Hoy, who won two golds in London after his success in the team sprint. "How can you top this?
"Glasgow is another question, as that would be the dream ending for me."
Trott's victory was her second of London 2012. She also won gold in the team pursuit with Dani King and Jo Rowsell.
Trott, 20, becomes the first female track cyclist to claim two golds at a single Games for Britain.
Momentous games for GB cyclists
"I can't believe this has happened to me, I really can't," said Trott.
Victoria Pendleton, who had already won the keirin, hoped to emulate Trott's feat but she was beaten in her individual sprint final by Australian rival Anna Meares.
"I'm just so relieved and I'm overwhelmed with emotion," said Pendleton, who is retiring after these Games. "I would have loved to have won in my final race. I'm glad that it's all done and I can move on."
Britain have now won seven of the 10 track cycling events at the London Velodrome.
Brownlee won Britain's first gold of the day with victory in the triathlon at Hyde Park, finishing ahead of younger brother Jonny, who took bronze.
Jonny needed treatment after collapsing with exhaustion as he crossed the finishing line, delaying the medal ceremony.
"It feels a bit underwhelming because Jonny has just collapsed," said Alistair. "It feels fantastic and the race was unbelievable."
He also praised the support he had received from the British public, adding: "I don't think I've ever come across anything like that. My ears were stinging. It was amazing."
Team GB then made it 20 golds when Laura Bechtolsheimer, Carl Hester and Charlotte Dujardin beat Germany to win the team dressage.
Nick Dempsey also won a medal, taking silver in the windsurfing.
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