Thousands of human rights protesters today disrupted the Olympic Torch Relay through London, billed as a journey of harmony and peace.
Scuffles broke out as the organised units of campaigners broke through the police and security cordons in a bid to snatch or even extinguish the flame.
Flashpoints in the difficult 31-mile journey from Wembley Stadium to Greenwich included Downing Street and the British Museum.
Prime Minister Gordon Brown greeted the torch behind Downing Street's closed steel gates in front of a vetted crowd as protesters scuffled with police outside and Beijing supporters waved Chinese flags and banged drums.
Campaigners are protesting against China's crackdown on pro-independence activists in Tibet and its human rights record. Falun Gong and the Burma Campaign are also demonstrating.
Instead of a smooth free-flowing journey by foot, open-topped bus, boat and bicycle, many of the 80 torchbearers were stopped on several occasions and encircled by Chinese torch officials and uniformed police officers protecting the flame from swooping protesters.
Two people were arrested in one of the most frightening incidents of the day when a protester surged on former Blue Peter presenter Konnie Huq as she ran with the torch in north west London.
Ms Huq told Sky News: "There was a bit of a skirmish with a protester but the flame stayed alight.
"I expected there to be protests but I was not expecting to be wrestled by people. I think that people feel very strongly about China and human rights but I guess that I am very lucky to be living in a country where people can have an opinion.
"I nearly lost my footing in the scramble but I kept going. I was aware when someone was lurching towards me and tried to grab it."
Two activists were taken away by police after attempting to put out the torch with fire extinguishers.
Martin Wyness and Ashley Darby were waiting with their equipment on the corner of Holland Park Avenue and Ladbroke Grove.
In a statement, the pair said the relay was a propaganda campaign by China to cover its "appalling human rights record".
"Like many people in the UK we feel that China has no right parading the Olympic torch through London," they said.
"Our protest is not directed at the Chinese people whatsoever but instead at the brutal Chinese regime that rules them."
Violinist Vanessa Mae was supposed to arrive by boat at the Royal Festival Hall - she did not. A welcome guard was ready and waiting but was never used.
Instead the crowd saw her appear there with the torch at a ceremony with Lord Coe, the London 2012 chairman.
Around 100 demonstrators tried to surround the torch and torch bearer in Fleet Street junction with Fetter Lane at about 2.39pm, according to Scotland Yard.
A spokesman said: "The decision was taken to place the torch and bearer back onto the bus and complete that stage on the vehicle, as per pre-determined police tactics. The route has not been altered."
By 3pm, 35 arrests had been made for a range of public order offences.
A heavy police presence was thrown over two large groups of protesters who had amassed at potential flashpoints of Downing Street and the British Museum.
About 500 gathered at Downing Street where former Olympic heptathlon champion Denise Lewis gingerly took the flame surrounded by police.
Several demonstrators attempted to run towards the torch, some trying to jump the barriers which lined the pavement.
Many were bundled to the floor by police, who were out on foot, on bicycles, and mounted on horseback.
The crowd reacted noisily, booing and whistling and shouting their protests.
Another 2,000 amassed at the British Museum where it was thought that Fu Ying, the Chinese Ambassador to London, would hand the flame on to Sir Clive Woodward.
She did not but appear there but at Chinatown where there was a warm and colourful welcome.
A Chinese Embassy spokesman said: "She took part. It was very successful, that is all I will say."
Amid snowfall at Wembley Stadium Britain's greatest Olympian, the five-times rowing champion Sir Steve Redgrave, took the first leg of the relay. He handed the flame to 16-year-old schoolgirl Cheyenne Green.
Tory leader David Cameron acknowledged many people were "very unhappy" about what was happening in Tibet, but he rejected calls for a boycott.
"I don't think we are at the stage yet where we should be considering a boycott," he told Sky's Sunday Live.
"I think having a policy of robust engagement with China is right."
Around 2,000 Metropolitan Police - including airborne, mounted and river units - were mobilised for the eight-hour event.
A mobile protective ring remained around the torch, including a team of police cyclists in a convoy of security, VIP and media vehicles.
Sports stars and celebrities are among torch bearers in the relay which is costing the Greater London Authority more than £40,000 to stage. Colourful and loud mini-carnivals were held along the route.
But campaigners, who say China has tainted the torch with its human rights record both at home and away, held protests along the route.
Pro-Tibet supporters waved banners and placards calling for Mr Brown to boycott the opening ceremony, for an end to killing in Tibet and for China to have talks with the Dalai Lama.
Hundreds lined Bayswater Road, many wearing Tibetan flags and carrying signs which read "Stop the killing in Tibet", "No Olympic torch in Tibet" and "China talk to Dalai Lama".
Helping to lead the chants was Buddhist monk Ngawang Khyentse, who said: "We can't just remain silent. We have no other choice than to protest because there is no other voice for Tibetans inside Tibet, so we have to speak out for human rights.
"At the very least the British government has to speak out and condemn the crackdown in Tibet. They must not keep silent."
When the bus travelled along Oxford Street, human rights campaigner Peter Tatchell stopped it in its tracks by jumping into the road holding a sign saying "Free Tibet, Free Hu Jia".
The Olympic torch has been a magnet for human rights protesters since it was lit in Greece last week.
Olympics Minister Tessa Jowell insisted that it would have been a "great mistake" not to have gone ahead with the relay.
She told BBC Radio 4's The World This Weekend: "I hope that the message that will go round the world is that, yes, there are many citizens of the UK who feel very strongly about China's human rights record, there are people in the UK who feel very strongly about the importance of dialogue with the Dalai Lama, and that in the UK we cherish the right to lawful and peaceful protest which, by and large, is what we have seen today."