New York Police Department tactical police officers stand guard near the New York Stock Exchange on September 9, 2011 in New York City. Officials are stepping up security in New York and Washington D.C. a day after U.S. officials received a credible but unconfirmed terror threat to utilize car bombs on bridges or tunnels in New York or Washington. (Photo by Justin Sullivan/Getty Images)

A gallery assistant holds a print of an Andy Warhol artwork estimated to fetch 1,500 GBP in Bonhams auction house on November 25, 2011 in London, England. The auction of prints of works ranging from old masters to contemporary artists takes place in London on November 29, 2011. (Photo by Oli Scarff/Getty Images)

(L-R) Mollie King and Frankie Sandford of The Saturdays performs for a dress rehearsal before the first night of their “All Fired Up!” tour at The Bournemouth International Centre on December 1, 2011 in Bournemouth, United Kingdom. (Photo by Dave J. Hogan/Getty Images)

A gallery assistant holds a rare 14th century time-telling device device in Bonhams auction house on December 9, 2011 in London, England. The instrument, which dates from 1396 and was discovered in a shed in Queensland, Australia, is due to be auctioned on December 13, 2011 and is expected to fetch 200,000 GBP. (Photo by Oli Scarff/Getty Images)

Charlotte Roirdan from Lyon & Turnbull views a letter written by Mary Queen of Scots on March 8, 2012 in Edinburgh, Scotland. The 450 year old letter, unearthed in Blair Castle in Ayrshire, has been verified as the hand writing of Mary Queen of Scotts and has been valued at 3,000 GBP. The letter, dated March 20, 1554, relieves the then laird of Blair from his duties due to gout and will be put up for sale next week at an auction in Edinburgh. (Photo by Jeff J. Mitchell/Getty Images)

A competitor tries to swipe away some grease as he slips off the “gostra”, a pole covered in grease, during the celebrations for the religious feast of St Julian, patron of the town of St Julian's, outside Valletta August 30, 2015. In the traditional “gostra”, a game stretching back to the Middle Ages, young men, women and children have to make their way to the top of a pole and try to uproot one of the flags to win prizes. Photo by Darrin Zammit Lupi/Reuters)