LONDON (Reuters) -The United States and Britain will announce agreements on technology and civil nuclear energy during U.S. President Donald Trump's unprecedented second state visit this week, as the UK hopes to finalise steel tariffs under a much-vaunted trade deal. Trump and his wife, Melania, will be treated to a display of British royal pageantry during their visit on Wednesday, including a carriage tour, a state banquet, a flypast by military aircraft and a gun salute. The British government hopes the soft power of the royals will appeal to Trump as it seeks tighter defence, security and energy ties with Washington, having already secured a favourable tariff deal.