A protester wears a pig mask as he marches through the streets of downtown Vancouver with thousands of people participating in the Occupy Vancouver protest on October 15, 2011 in Vancouver, British Columbia, Canada. Thousands of people are taking to the streets in cities across the world today in demonstrations inspired by the Occupy Wall Street protest in New York City. An estimated 2,000 people participated in the Vancouver occupation. (Photo by Jeff Vinnick/Getty Images)

British Gas engineer Martin Caulfield, 69, services and cleans a gas lamp in front of Big Ben on October 31, 2011 in London, England. Caulfield has been looking after the traditional lights since 1982. There are still around 1600 left in the capital. (Photo by Matthew Lloyd/Getty Images)

British sprinter Dina Asher-Smith arrives at The Fashion Awards 2018 In Partnership With Swarovski at Royal Albert Hall on December 10, 2018 in London, England. (Photo by Mike Marsland/BFC/Mike Marsland/Getty Images)

A handout photo provided by the Police department in Lippe on 01 June 2015 of a British “Challenger 2” tank after it rolled over a car's front in Lippe, Germany, 01 June 2015. Police reported that a 18-year old female driving beginner from Detmold apparently overlooked a convoy of tanks when she turned left onto the Panzeringstrasse (lit. Tank Ring Road). (Photo by EPA/Polizei Lippe)

Descending into the Marum Volcano in Vanuatu, Intrepid explorers found an unusual way of staying warm this winter by spending Christmas day on an active volcano. British climber Chris Horsley, 22, and his friends Gareth Hawken, 30, Geoff Mackley, 50, and Bradley Ambrose, 36, from Auckland, New Zealand, hiked up the Marum Volcano, Vanuatu, on the morning of the 25th. Instead of passing the day with their families, the team climbed down a 1200ft cliff to get close to a flowing lake of lava. (Photo by Bradley Ambrose/Caters News)

Chinese soldiers leave after Chinese President Xi Jinping inspected troops of People's Liberation Army (PLA) Hong Kong Garrison at the Shek Kong Barracks in Hong Kong, Friday, June 30, 2017. Xi landed in Hong Kong Thursday to mark the 20th anniversary of Beijing taking control of the former British colony, accompanied by a formidable layer of security as authorities showed little patience for pro-democracy protests. (Photo by Kin Cheung/AP Photo)

European Space Agency astronaut Tim Peake will return home after a six-month long mission on the International Space Station,on June 18, 2016. Peake was the first British ESA astronaut to visit the ISS and captured hundreds of photographs of the Earth during his mission. Here: “Lots of sun-glint right now during our whole orbit – we haven't seen a sunset for over 3 days”, he wrote. (Photo by Tim Peake/ESA/NASA)

Passengers pose for a selfie as they wait for the Night Tube train service at Oxford Circus on the London underground system in London, Britain August 20, 2016. The London Underground is starting its first-ever overnight service, a move city leaders hope will make the British capital a truly 24-hour city and bolster the local economy. (Photo by Paul Hackett/Reuters)