State visits are formal trips to the UK by the head of a country, usually arranged at the invitation of the monarch, acting on government advice. They are grand occasions with lots of pageantry, but governments also use state visits to further Britain's interests. Second-term US presidents, who have already made a proper state visit, are usually treated to tea or lunch with the monarch at Windsor Castle on a formal UK trip, as was the case for George W Bush and Barack Obama. That's instead of