South African President Cyril Ramaphosa on Monday landed in Britain ahead of the first state visit hosted by King Charles III as monarch.
Ramaphosa arrived at London Stansted airport on a South African Air Force jet, and was met by a British military guard of honour.
The official programme starts on Tuesday and will include a state banquet at Buckingham Palace.
The last state visit to the UK came in June 2019, when Queen Elizabeth II hosted US president Donald Trump and his wife Melania.
Climate change, trade and Charles´s vision for the Commonwealth are expected to be on the agenda.
Ramaphosa was last in London for the state funeral of the queen at Westminster Abbey in September.
Charles and Queen Consort Camilla will be in charge of welcoming Ramaphosa and First Lady Tshepo Motsepe but will also see the visiting couple meet other senior royals.
Heir to the throne Prince William and his wife Kate, Princess of Wales, will take him to join Charles and Camilla for a ceremonial military welcome.
Charles´s youngest brother Prince Edward has also been recruited to accompany Ramaphosa to London´s Kew Gardens and a biomedical research centre.
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