King Charles and Camilla, the Queen Consort, welcomed Cyril Ramaphosa on Tuesday at the beginning of his two-day visit to the UK. It is the King's first state visit since he ascended the throne in September, and the first in more than three years due to the pandemic.
Mr Ramaphosa also met with the Prince and Princess of Wales.
During a visit to the Buckingham Palace Picture Gallery, the South African president was shown around an exhibition of Royal Collection artefacts.
Mr Ramaphosa picked up a photograph of the late Queen side by side with Mr Mandela at the state banquet in the Palace in 1996, saying: "This lovely picture."
The King remarked "you were lucky to have known both".
Mr Ramaphosa went on to address MPs and officials in the Royal Gallery at the Palace of Westminster.
The evening continued with a white-tie state banquet at Buckingham Palace.
The Princess of Wales wore a pearl bracelet belonging to the late Queen, as well as Diana, Princess of Wales's earrings, at the banquet.
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