The Olympic flame will be cheered through the grounds of Buckingham Palace by the Duke and Duchess of Cambridge later.
A host of celebrities have been lined up to carry the torch past locations including St Paul's Cathedral, Trafalgar Square, Downing Street and the West End the day before its 70-day, 8,000-mile journey ends.
Scout volunteer Jon Sayer will have the honour of carrying the flame to the gates of the Queen's official London home this evening where he will meet the Duchess.
The 33-year-old, who last year saved a man from drowning, was chosen to take part in the relay after the Duchess asked for a fellow Scout to run this leg of the event.
Mr Sayer, from Todmorden in West Yorkshire, is one of three volunteers helping to carry the Olympic flame through the palace.
The others are John Hulse, who was nominated by Prince William's charity Mountain Rescue, and Wai-Ming Lee from MapAction, which was put forward by its royal patron Prince Harrry.
On day 69 of the nationwide relay the torch is being carried 32.7 miles through the London boroughs of Camden, Islington, City of London, Southwark, Lambeth, Wandsworth, Hammersmith and Fulham, Kensington and Chelsea and Westminster.
Its journey began at 6.48am with Clive Woodward, Team GB's deputy chef de mission and manager of the England 2003 World Cup Rugby winners, starting it off from the Roundhouse in Camden.
Comedian and charity fundraiser David Walliams carried the flame at 8.24am outside Islington Town Hall before it made its way to the City of London, St Paul's Cathedral and the Millennium Bridge, from where it moved to Shakespeare's Globe.
Rugby heroes Lawrence Dallaglio and Lewis Moody and the actress Joanna Lumley were among other celebrities carrying the flame.
The torch bearers were also due to include Gill Hicks, who lost both legs in the 7/7 terror attacks that killed 52 people on the day after London won the Games back in 2005.
She was advised not the make the trip from Australia where she now lives and so nominated London Ambulance Service medic Tracy Russell to take her place.
After visiting the Palace, the torch will end the day in Hyde Park at 7.10pm where a celebration cauldron will be lit on stage before a concert with Dizzee Rascal, The Wanted, Mark Ronson and Katy B, Eliza Doolittle and Wretch 32 among the performers.