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How to organise a successful flashmob event

31 May 2011 Last updated at 07:59 BST

Hundreds of people were taken by surprise in central London on Monday when crowds in Covent Garden and Trafalgar Square suddenly burst into a song and dance routine.

David Sillito spent the day with Max De Lucia and Fred Feeney of the London Flashmob choir to find out how to organise a successful event.