A chimpanzee bottle-feeds a lamb at Southam Zoo Farm in Warwickshire. The owners of the zoo, Mr and Mrs Clews, bring up many of the animals as their pets; the animals, are, as a result, of a friendly disposition. (Photo by Fox Photos/Getty Images). 23rd August 1968

An Aden civilian crouching in terror as British soldiers threaten him during Arabian demonstrations in Crater. (Photo by Express Newspapers/Getty Images). 1967

A worker pauses for a sandwich, resting on a girder during the construction of a skycraper. (Photo by Hulton Archive/Getty Images). Circa 1930

Three workers demonstrating the different types of gas masks used in mine rescue work. (Photo by Fox Photos/Getty Images). December 1925

Queen Elizabeth II (as Princess Elizabeth) writing at her desk in Windsor Castle, Berkshire. (Photo by Lisa Sheridan/Studio Lisa/Getty Images). 30th May 1944

View of an American marine as he lies in a foxhole and whistles at a husky, one of the scouting dogs used during the landing on Guam, August 1944. (Photo by W. Eugene Smith/Time & Life Pictures/Getty Images)

Filipino barefoot Catholics carry a replica of the Black Nazarene during a procession ahead of the Black Nazarene feast day celebrations in Manila, Philippines, 07 January 2016. The procession of the Black Nazarene is expected to draw millions of barefooted Catholic devotees to Manila on 09 January, according to a Manila police official. (Photo by Francis R. Malasig/EPA)

Shannon McGurgan (Bottom), Farhad Ahadi (Middle) and Malia Walsh (Top) perform the Circus Trick Tease on stage at a media call ahead of the inaugural Melbourne Circus Festival on September 23, 2011 in Melbourne, Australia. The National Institute of Circus Arts will showcase artists from around the world during the first ever circus festival in Melbourne from September 26 – October 2. (Photo by Hamish Blair/Getty Images)