Prince William exchanges rings with his bride Catherine Middleton in front of the Archbishop of Canterbury Rowan Williams inside Westminster Abbey on April 29, 2011 in London, England. The marriage of Prince William, the second in line to the British throne, to Catherine Middleton is being held in London today. The marriage of the second in line to the British throne is to be led by the Archbishop of Canterbury and will be attended by 1900 guests, including foreign Royal family members and heads of state. Thousands of well-wishers from around the world have also flocked to London to witness the spectacle and pageantry of the Royal Wedding. (Photo by Dominic Lipinski - WPA Pool/Getty Images)

A recruitment drive during the First World War at Trafalgar Square, London. (Photo by Central Press/Getty Images)

Father Christmas waiting for a bus in the London West End with his reindeer and a sack of presents. (Photo by Evening Standard/Getty Images). 12th August 1970

Parked scooters and motorcycles in a line on January 13, 2012 in London, England. Statistics showed a 12% increase in scooter registration in 2011, with cost savings on petrol, parking and congestion charge (in London) believed to be the primary factor. (Photo by Matthew Lloyd/Getty Images)

Giant Olympic rings are towed on The River Thames past The Tower of London on February 28, 2012 in London, England. (Photo by Peter Macdiarmid/Getty Images)

Lara Stone at Mark's Club on October 27, 2016 in London, England. (Photo by Mark Milan/GC Images)

Immigrants from the West Indies at Victoria Station in London, 1956. (Photo by Hulton-Deutsch Collection/CORBIS/Corbis via Getty Images)

Cheerleaders wait to perform before the New Year's Day parade in London, Britain January 1, 2017. (Photo by Neil Hall/Reuters)