Decorative model Elephants stand in Trafalgar Square on May 4, 2010 in London, England. 260 of the decorative life size baby Elephants have been designed by established and emerging artists including Paul Smith, Marc Quinn and Julien Macdonald and have been placed across the capital in prominent places such as Buckingham Palace, Parliament Square and Trafalgar Square. (Photo by Dan Kitwood/Getty Images)

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

A mass pillow fight in Trafalgar Square in central London on April 5, 2014 on International Pillow Fight Day. (Photo by Jane Scanlan)

A woman photographs a Norwegian spruce Christmas tree from Oslo after it was lit at Trafalgar Square in central London, December 4, 2014. (Photo by Toby Melville/Reuters)

Three members of English pop group The Tremeloes; Chip Hawkes, Alan Blakley and Dave Munden, kissing their brides; Carol Dilworth, Lyn Stevens and Andree Wittenberg, in Trafalgar Square, London. (Photo by Wesley/Getty Images). 1967

One of Jesus' disciples is dunked in a fountain during The Wintershall's “The Passion of Jesus” in front of crowds on Good Friday at Trafalgar Square on March 25, 2016 in London, England. (Photo by Chris Ratcliffe/Getty Images)

A sculpture entitled “Powerless Structures, Fig.101” designed by Danish artist Michael Elmgreen and Norwegian artist Ingar Dragset is unveiled on the Fourth Plinth in Trafalgar Square on February 23, 2012 in London, England. (Photo by Oli Scarff/Getty Images)

Actress Emma Watson attends the World Premiere of Harry Potter and The Deathly Hallows – Part 2 at Trafalgar Square on July 7, 2011 in London, England. (Photo by Ian Gavan/Getty Images)