Law enforcement officers stand, with some turning their backs, as New York City Mayor Bill de Blasio speaks on a monitor outside the funeral for NYPD officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. Tens of thousands of law enforcement officers from across the country gathered on Sunday for the funeral of the second of two New York City policemen killed last month in an ambush that galvanized critics of Mayor de Blasio. (Photo by Shannon Stapleton/Reuters)

Muslim pilgrims pray around the holy Kaaba at the Grand Mosque, during the annual haj pilgrimage in Mecca September 30, 2014. (Photo by Muhammad Hamed/Reuters)

A passenger waits after his train arrived in Nouadhibou, Mauritania’s second largest city and the main export port for the country’s iron ore industry, on June 25, 2014. The mining company’s employees proudly call their firm the lung of their nation's economy and the train that ferries the ore to the coast stretches some two kilometres, making it one of the world's longest. SNIM mines black iron ore in the northern town of Zouerate, a remote desert location which nevertheless attracts people from all over the country looking for work. (Photo by Joe Penney/Reuters)

A solar-powered plane takes off from Jiangbei International Airport in southwest China's Chongqing Municipality, Tuesday, April 21, 2015. The Solar Impulse 2 departed Chongqing on Tuesday for a 1190-kilometer (642-mile) flight to the city of Nanjing in eastern China, the sixth leg of its around-the-world flight. (Photo by Chinatopix via AP Photo)

A Palestinian reveller takes part in a colours festival organized by Palestinian activists in the West Bank city of Ramallah August 20, 2015. The festival is inspired by the Hindu spring festival of Holi. (Photo by Mohamad Torokman/Reuters)

Women dance in costume during the West Indian Day Parade in Brooklyn, New York September 7, 2015. The parade, which takes place annually, celebrates Caribbean culture and history. (Photo by Andrew Kelly/Reuters)

Residents walk past an overturned car as the cleanup begins from severe flooding in White Sulphur Springs, W. Va., Friday, June 24, 2016. (Photo by Steve Helber/AP Photo)

Giffords Circus’s show is touring the UK. Established in 2000, Giffords Circus is a small circus company that delivers circus / theatre fusion to the villages and market towns of the south west. It combines dance, comedy, horses and live music in a two-hour show, located on village greens in a small white tent surrounded by handmade burgundy and gold showman’s wagons. Photographer Tom Pilston goes behind the scenes to meet the performers. Here: The incredible, gravity-defying Konjowoch Troupe. (Photo by Tom Pilston/The Guardian)