The King's Troop Royal Horse Artillery fired a traditional 41 Gun Royal Salute at Green Park today, to mark the Queen's 88th Birthday. Queen Elizabeth is spending the day in private at Windsor Castle.
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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.