People look at the new style London bus after its launch at Trafalgar Square in London

People look at the new style London bus after its launch at Trafalgar Square in London December 16, 2011. The more environmentally friendly bus is based on the popular old Routemaster design and will enter service at the beginning of next year. REUTERS/Luke MacGregor

A breakaway group of protesters begin to set up tents in Trafalgar Square as students take part in a demonstration against higher tuition fees

LONDON, ENGLAND - NOVEMBER 09: A breakaway group of protesters begin to set up tents in Trafalgar Square as students take part in a demonstration against higher tuition fees and privatisation in universities on November 9, 2011 in London, England. Around 4000 police officers are on duty and are to

An Unidentified member of the public reacts in Trafalgar Square, central London to the International Olympic Committee's announcement from Singapore that London has won the bid to host the 2012 Olympic Games, Wednesday July 6, 2005. Candidate cities competing for the Olympic bid were London, Paris,

Security Alert Closes Whitehall In Central London

LONDON, ENGLAND - JULY 27: Police officers close Whitehall near Trafalgar Square in Central London after a suspicious package was reported on July 27, 2011 in London, England. Security is high around Trafalgar Square, which will host a ceremony tonight to mark the one year countdown to the Olympic