Britain's Queen Elizabeth II (centre L) accompanied by her husband Prince Philip, Duke of Edinburgh greet wellwishers during a 'walkabout' on her 90th birthday in Windsor, west of London, on April 21, 2016. Britain celebrates Queen Elizabeth II's 90th birthday on Thursday, with her eldest son Prince Charles paying tribute in a special radio broadcast and Prime Minister David Cameron leading a parliamentary homage. / AFP / JUSTIN TALLIS (Photo credit should read JUSTIN TALLIS/AFP/Getty Images)
