US President and First Lady Jill Biden arrived at London Airport on Air Force One just before 10pm on Saturday. US President Joe Biden and First Lady Jill Biden exit Air Force One upon arrival at Stansted Airport (REUTERS) Mr Biden is expected to sign the official book of condolences and attend a reception at Buckingham Palace on Sunday, hosted by King Charles III. On Monday, she will join a host of world leaders at Westminster Abbey to pay their respects to the late monarch. The Bidens were warmly welcomed at the airport by US Ambassador to the UK Jane Hartley, Lord Lieutenant of Essex Jennifer Tolhurst and a number of other high-ranking officials. Joe and Jill Biden leave London Stansted Airport in their motorcade (PA) The Bidens are flanked by a motorcade on their way to London (PA) The US president and his wife were later photographed leaving Stansted Airport in their motorcade, seated in an armored state car – the same one that takes him on any trip away from the White House, known to US intelligence as “The Beast”. . After the Queen’s death, Biden issued a proclamation ordering all US flags to be flown at half-staff “as a mark of respect to the memory of Queen Elizabeth II” until sunset on the day of her burial. Before making the flight to London, he spoke to the new King to express his condolences. Mr Biden “passed on the great admiration of the American people for the Queen” to her son and credited her “dignity and stability” with “deepening the enduring friendship and special relationship between the United States and the United Kingdom”. US Ambassador Jane Hartley greets the Bidens as they disembark from Air Force One at Stansted Airport (AFP via Getty Images) Monday’s elaborate ceremony will see the Queen taken from Westminster Hall to Westminster Abbey and finally to Windsor Castle, the route of which is expected to draw tens of thousands. Heads of state and overseas government representatives, including foreign royals, governors-general and prime ministers of the realm will first gather at the Royal Hospital, Chelsea, and travel under “collective arrangements” to Westminster Abbey. People pay tribute to Queen Elizabeth as she lies in state at Westminster Hall (via REUTERS) Among the 2,000 guests are other representatives of the realms and the Commonwealth, Orders of Chivalry including recipients of the Victoria Cross and the George Cross, the government, parliament, parliaments and delegated assemblies, the Church and its patrons Her Majesty. Additional representatives of legal, emergency services, civil servants and professions, as well as public representatives will also make up the congregation.