A crowd of 60,000 people in Hyde Park have given a rapturous welcome to the Olympic flame on the penultimate day of the torch relay round the UK.
Under blue skies, the flame was carried into the central London park by Tyler Rix, 19, where he lit a gold cauldron on a concert stage.
Earlier, the relay was greeted at Buckingham Palace by Princes William and Harry and the Duchess of Cambridge.
It spent the day visiting landmarks, including St Paul's and Downing Street.
Mayor Boris Johnson told the crowd: "I've never seen anything like this in all my life.
"I think the excitement is growing so much that the Geiger counter of Olympomania is going to go 'zoink' off the scale."
As the crowd chanted his name, the Mayor predicted that Team GB would "win more gold, silver and bronze medals than you need to bail out Greece and Spain together".
It was the final full day of torchbearing for the 70-day relay before the flame is taken to the Olympic Park on Friday for the opening ceremony.
Team GB's Deputy Chef de Mission Sir Clive Woodward kicked off Thursday's proceedings at Camden's Roundhouse music venue just after 06:45 BST.
He was coach of the England rugby union team between 1997 and 2004, leading them to glory in in the 2003 Rugby World Cup.
Half an hour later the flame was carried on a boat on Regent's Canal to Granary Square and shortly after it was carried in front of the Olympic Rings in St Pancras Station.
Luke Corduner, 32, from Camden who was nominated for being "a great PE teacher", ran through the station arcade, climbed the Great Glass Stairway and posed for a photograph by the statue of John Betjeman and a Eurostar train.
Comedian David Walliams took up the flame at Islington Town Hall in recognition of his contribution to sport in the charity events he has undertaken.
Walliams swam the English Channel in 2008, the Strait of Gibraltar in 2008 and he cycled from John O'Groats to Land's End in 2010.
Last year, he swam the length of the River Thames and in total has raised £8.5m for Comic Relief and Sport Relief.
During the day the flame went to Shakespeare's Globe, Stamford Bridge, the home of Chelsea Football Club and the Opera Stage steps at Holland Park.
It visited St Paul's Cathedral where there was a performance from Jazz at Lincoln Center Orchestra .
A short time later, wheelchair basketball Paralympian Ade Adepitan carried it over the Millennium Bridge.
Among the celebrities was Bollywood actor Amitabh Bachchan and Ab Fab stars Jennifer Saunders and Joanna Lumley.
It was carried there by Antoine de Navacelle, the great grand-nephew of Baron Pierre de Courbetin, the father of the modern-day Olympics.
He passed the flame to Sir Bruce Forsyth, a British television light entertainment stalwart since the 1950s, who struck a few familiar poses as well as dancing a few steps with the torch in hand.
In the City of Westminster the flame travelled by open-top bus along Oxford Street to the shopping hub of Oxford Circus before turning down Regent Street towards the theatres of the West End.
At Trafalgar Square, Patrick Kane, 15, from Camden, carried the flame. He is a double amputee and was the youngest person to be fitted with an advanced bionic hand prosthesis.
Shortly afterwards, service-woman Kate Nesbitt, who was awarded the Military Cross for bravery in 2009, took the flame into Downing Street, handing it over to Florence Rowe, 81, outside Number 10.
The flame travelled along Birdcage Walk to the front of Buckingham Palace where Wai Ming-Lee, 38, from Hemel Hempstead, carried it into Buckingham Palace.
The Duke and Duchess of Cambridge and Prince Harry watched the "torch kiss" between Wai and the next torchbearer John Hulse who carried it out of the palace and was joined by members of the Household Cavalry along Constitution Hill.
The royal theme was heralded on Wednesday when Prince Charles and the Duchess of Cornwall turned out to watch the relay in Tottenham .
The Queen and Prince Philip have also seen the torch when it visited Windsor Castle earlier in July.
On Friday the flame sets off on its final day from Hampton Court Palace.
It will travel in a cauldron on board Gloriana and be carried at different points along the river by seven torchbearers.
The flame will be carried into City Hall at lunchtime before re-emerging later to light the cauldron in the Olympic Park to signal the official opening of London 2012.