Emperor Naruhito and Empress Masako of Japan are beginning a three-day state visit to the UK.
They will receive a ceremonial welcome and a carriage ride up the Mall, with a state banquet hosted by King Charles III at Buckingham Palace.
But because of the general-election campaign, the Japanese royal couple will not make a trip to Downing Street.
The Princess Royal will also be absent from the state banquet, after being admitted to hospital following a head injury thought to have been caused by a horse.
Royal greeting
State visits are a mix of ancient pageantry and modern international politics, with the red carpet being rolled out for important visitors.
The visit by the emperor and empress is intended to reinforce military, scientific and cultural links between the UK and Japan.
It is the first by a Japanese head of state since 1998 and will begin with a formal royal greeting at Horse Guards Parade and then a procession to Buckingham Palace.
State visits during a general election are unusual – in the past, they have been rescheduled to avoid a clash with the political campaigning.
But the Japanese visit has gone ahead, without the usual meeting with the prime minister in 10 Downing Street.
A centrepiece of this diplomatic flattery is the state banquet in the lavish surroundings of the ballroom of Buckingham Palace.
The King will toast his visitors at such events, often in their own language, and make a speech in honour of his guests.
The emperor will then reply.
Prime Minister Rishi Sunak and Labour leader Keir Starmer will be at the state banquet, on Tuesday evening, in one of the last such formal occasions before next week’s election.
Nostalgic return
The following night, the two party leaders are in a head-to-head TV debate.
The emperor and empress’s programme of visits over the next few days will include Westminster Abbey, the Francis Crick Institute, Kew Gardens and the Royal College of Music.
They will lay a wreath on Elizabeth II’s tomb, in St George’s Chapel, Windsor.
And on Friday, after the state visit has ended, they will make a nostalgic return to their former colleges at Oxford University, where they were both students.
