A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

The Photographers 2015 runs from 25 November to 23 December at Osborne Samuel and Beetles+Huxley, London. Here: Untitled, 1950, by Bert Hardy. (Photo by Bert Hardy/Beetles+Huxley & Osborne Samuel)

Jewels Lewis poses as the first customer to purchase the new Apple iPad 2 at Apple Store, Regent Street on March 25, 2011 in London, England. The latest iPad went on sale in the UK at 5:00pm.

Kylie Minogue performs at the Cardiff International Arena on March 25, 2011 in Cardiff, Wales. (Photo by Matt Cardy/Getty Images)

Model Adriana Sklenarikova Karembeu presents new “Pikolino” shoes at El Corte Ingles store on April 1, 2011 in Madrid, Spain. (Photo by Carlos Alvarez/Getty Images)

Bonhams expert Michaela Vergottis holds a yellow Jade Chinese Imperial Sceptre on May 9, 2011 in London, England. The piece which is thought to have been taken by British Troups during the Boxer Rebellion is expected to fetch between £800,000 – 1.2 M GBP when it goes on sale at the “Chinese Art” sale at Bonham's auction house on May 12, 2011. (Photo by Dan Kitwood/Getty Images)

A dancer from the Trisha Brown Dance Company performs during “Roof Piece” above the High Line park June 9, 2011 in New York City. Roof Piece (1971) consists of nine dancers performing improvised movement signals to each other in a chain on various rooftops overlooking the city. This presentation marked the first full performance of the piece since 1973. (Photo by Mario Tama/Getty Images)

A Polish MiG-29 flies beneath dark skies at the annual RNAS Yeovilton Air Day on July 9, 2011 in Yeovil, England. The annual air day at RNAS Yeovilton in Somerset, attracts over 35,000 people to what is one of the biggest air shows in the region and gives visitors the chance to see a host of aircraft as well as a number of historic and classic cars. (Photo by Matt Cardy/Getty Images)