A man arranges a display of cacti during preparations for the RHS Chelsea Flower Show in London, Britain May 21, 2016. (Photo by Neil Hall/Reuters)

People hold out money as butchers sell their remaining produce of the year at discounted prices during the traditional Christmas Eve auction at Smithfield's market in London December 24, 2015. (Photo by Neil Hall/Reuters)

Battersea Power Station. The chimney rims are thinner on top than you might expect. (Photo by Bradley L. Garrett)

A man sits waiting for a train on the London Underground in 1890, when the platform floors were still made from wooden floorboards. (Photo by Hi-Story/Alamy Stock Photo)

Competitors take to the streets of the capital in fabulous fancy dress costumes during the Virgin London Marathon 2012 on April 22, 2012 in London, England. (Photo by Mirror.co.uk)

In this combination image visitors to the London Super Comic Convention dress as their favourite Marvel comic characters at ExCel on February 25, 2012 in London, England. Visitors to the Comic Convention are encouraged to wear a costume of their favourite character. (Photo by Peter Macdiarmid/Getty Images)

A “jungle nymph” is measured during the annual weight-in ZSL London Zoo on August 21, 2014 in London, England. The height and mass of every animal in the zoo, of which there are over 16,000, is recorded and submitted to the Zoological Information Management System. This is combined with animal measurement data collected from over 800 zoos and aquariums in almost 80 countries, from which zoologists can compare information on thousands of endangered species. (Photo by Oli Scarff/Getty Images)

Revellers watch as police officers dance in the street at the Notting Hill Carnival in west London, August 30, 2015. (Photo by Toby Melville/Reuters)