President Cyril Ramaphosa on Tuesday received two letters from Queen Elizabeth II that the late former president Nelson Mandela had written.
The exchange took place during his visit to Windsor Castle.
"She was reminiscing about her relationship with Nelson Mandela, particularly on the year when we celebrate 100 years of his birth," he said after the visit.
"She remembered very fondly the discussions she used to have with him. She also gave me two letters that he wrote to her, wonderful pieces of memorabilia."
The letters marked South Africa's re-entry to the Commonwealth in 1994, according to the Royal Family's official Twitter account.
Ramaphosa is in the UK on a working visit to London to attend the Commonwealth Heads of Government Meeting, which will take place on Thursday and Friday.
President Cyril Ramaphosa meeting with British Prime Minister Theresa May ahead of CHOGM to be held in London from 19th to 20th April 2018 pic.twitter.com/heU2KHABdr— PresidencyZA (@PresidencyZA) April 17, 2018
He met with British Prime Minister Theresa May for a bilateral meeting and agreed on a deal worth £50m (R857m) to help South Africa improve its business environment.
"We focused largely on the economy and how our partnership between SA and the UK can be deepened around economic matters, the economic growth we are trying to drive," Ramaphosa said.
President Cyril Ramaphosa held a bilateral meeting with the UK Prime Minister Theresa May. President Ramaphosa is on a working visit to London, to attend the Commonwealth Heads of Government meeting scheduled to take place from the 19th - 20th Apri. #CHOGM2018pic.twitter.com/eJRYgCSFvr— South African Government (@GovernmentZA) April 17, 2018
He said May was "quite enthusiastic" about assisting and wanting to find ways in which to play a role.
Ramaphosa said they would be trawling "the whole world" to try and campaign for investments in South Africa.