The Olympic flame has arrived in the host city in dramatic style, being abseiled into the Tower of London from a Royal Navy Sea King helicopter at the fitting time of 20:12 BST.
The Sea King took off from Guildford at the end of day 63 of the torch relay.
Earlier, a 17-year-old was arrested after trying to grab the flame as the torch relay passed through Gravesend.
He sped out of the crowd towards the torchbearer and was wrestled to the ground by Torch Security Team officers.
After Royal Marine Martin Williams abseiled with the flame into the Tower of London, Dame Kelly Holmes - who won the 800m and 1500m gold medals in the Athens 2004 Olympic Games - became the capital's first torchbearer as she carried the flame on to the ramparts of the Tower.
She handed the flame to Abul Kasam, 30, who was selected as a torchbearer for his voluntary work in the borough of Tower Hamlets, and who carried the flame into a reception for invited guests at the Jewel House.Dignitaries present included Locog Chairman Sebastian Coe, Mayor of London Boris Johnson, Mayor of Tower Hamlets Lutfur Rahman and General the Lord Dannatt, Constable of the Tower of London.
Lord Coe said the Tower of London was a fitting entry point for the Olympic flame in to London as "it is where the power and the significance of the Monarch resides, while it also houses London 2012's medals - all 1,760 tonnes of them are secreted about this building somewhere".
He said that in the nine weeks of the Olympic torch relay so far, more than 10 million people had come out to more than 1,000 towns, villages and cities to celebrate not just the flame but the extraordinary contribution of the torchbearers' to London 2012.
Mr Johnson added of the Tower's significance: "As Henry VIII discovered, with at least two of his wives, it was the perfect place to bring an old flame."
He said tomorrow the flame would begin its procession through London until "millions of Londoners have seen the flame with their own eyes and, as it spreads through the city, I know its radiance will dispel any last remaining clouds of dampness and anxiety that may hover over some parts of the media in this country".
The flame was to take part in the Tower's ancient Ceremony of the Keys - before being taken to the Queen's House by Lord Dannatt for safe keeping overnight.
Day 63 of the relay covered 105 miles, and the attempted torch-grabbing incident happened at 09:55.
Torchbearer Anna Skora, 23, from Lublin in Poland swerved out of the way but continued with her section of the relay.
"I remember the sight of this guy, he jumped to me," She told BBC South East. "This moment I remember [then] some security go to me."
The youth was arrested by Kent Police and the Metropolitan Police, from which the torch security officers are drawn, said: "We would like to remind members of the public not to attempt to breach the security bubble around the torchbearer."
Earlier the flame was carried on a boat at Maidstone Rowing Club and later moved on to Brands Hatch.The motor racing venue will be the base for the road cycling events of the 2012 Paralympics, starting on 30 August.
Craig Preece, a former soldier who lost his leg in an incident in Afghanistan, rode on to the track with the flame.
Another of the day's 140 torchbearers was Olympic medallist Roger Black.
A hugely popular athlete during the 14 years he represented Great Britain, Black won silver in the 400m and in the 4x400m relay at the Atlanta Games in 1996 and a bronze in the 4x400m relay at the 1992 Barcelona Games.
He carried the flame in Godalming, the penultimate of 21 communities the relay travelled through on Friday.
Throughout the day the flame was carried through Maidstone, Gillingham, Chatham, Rochester, Higham, Gravesend, Brands Hatch, Borough Green, Seal, Sevenoaks, Riverhead, Godstone, Bletchingley, Redhill, Reigate, Dorking, Westcott, Shere, Chilworth, Godalming and Guildford.
An evening celebration was held at Guildford's Stoke Park, with a cauldron-lighting ceremony and entertainment from Rizzle Kicks and Twist and Pulse.