Updated: April 30, 2013, 12:00 AM
In pictures: Sheikh Khalifa's state visit
epa03682247 United Arab Emirates (UAE) President Sheikh Khalifa Al-Nahyan (R) is welcomed by Britain's Queen Elizabeth II and the Duke of Edinburgh (right) at Windsor Castle near London 30 April 2013. The president is on a two day state visit to Britain amid claims that three Britons who were sentenced to four years in prison by a Dubai court over drug charges, 29 April, were tortured during their detention. EPA/ANDY RAIN *** Local Caption *** 03682247.jpg