Team London Ambassadors - the volunteers who helped make the London 2012 Olympics such a success - staged a flash mob dance in St Pancras station today.
It's the first time the volunteers have returned since the end of the Games - but the Mayor of London is hoping it won't be the last.
Boris Johnson is planning to harness the volunteer manpower in a long-term programme, with initial pilots taking place over the next two weeks.
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Tree surgeon Ben Atkinson could be seen balancing on beams half way up the tower.
The flag was seen flying from the scaffolding around Big Ben.
Campaigners calling for a second referendum on Brexit are set to march through central London at midday.