Thousands, if not millions, of people are expected to see the Queen lying in state from this Wednesday (September 14).
Westminster Hall will be open 24 hours a day for four days for crowds to view the Queen's coffin. However, officials are warning of huge queues that could last hours.
Official government guidance states: "If you wish to attend the Lying-in-State, please note there will be a queue, which is expected to be very long. You will need to stand for many hours, possibly overnight, with very little opportunity to sit down as the queue will be continuously moving."
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Visitors will have limits on what they can have on their person, and will need to go through an airport-style security system on arrival. Anyone found to be intoxicated, or jumping the queue, will be removed from the queue.
People are being told to "dress appropriately" and not to wear clothes with political or offensive slogans. You must also turn your phone off, and no film or photography is allowed.
Rail firms are also warning trains will be "extremely busy". The Rail Delivery Group's customer information director told the BBC people needed to plan carefully and allow plenty of time if planning to travel during the official mourning period.
Transport for London also warned roads and public transport in central London will be very busy and has advised travellers to allow "plenty of extra time" for their journeys and to avoid driving where possible. Andy Byford, London's Transport Commissioner, told the Beeb: "We are working with our partners to keep our city moving smoothly and to ensure that everyone who is planning to attend the memorial events can do so safely."
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