Prince has one-to-one meeting with prime minister in one of his last official engagements

The Duke of Sussex has met Boris Johnson and other world leaders attending the UK-Africa Investment Summit in London during what is likely to be one of his few remaining engagements as an official royal.

Hours after a speech in which he spelled out he and Meghan felt they had “no other option” but to step away from royal life, he arrived at London Docklands, where the prime minister was hosting the event. The two had a 20-minute private “catch-up”, without aides present.

Harry, who spoke on Sunday of his great sadness “that it has come to this”, will leave for Canada in the near future to join Meghan and their baby son, Archie. The couple will spend the majority of their time in Canada as they begin a one-year transition period to their roles as royal outsiders.

It was not a decision he had made lightly, he said, describing it as a “leap of faith”. There are not thought to be any engagements in his diary for the latter part of this week.

No date has been given for when the prince will officially step down as a working royal, and no longer be able to represent the Queen in any official capacity. Aides have only said it will be in the spring.

It is thought Harry could conduct a small number of royal engagements, possibly in the UK, before retiring from official royal life, though there is no indication of when Meghan might return to Britain.

Though barred from using their HRH – His or Her Royal Highness – titles, the couple have not been stripped of them. Neither have they been required to give up Frogmore Cottage, their official UK residence on the Windsor estate, though they will repay the £2.4m refurbishment costs met by the public purse. This indicates there has been no burning of bridges by the Queen, allowing the couple a possible way back in future.

Harry said in his speech: “Our hope was to continue serving the Queen, the Commonwealth, and my military associations without public funding. Unfortunately that wasn’t possible.”

The risk of the royal family’s reputation being tarnished by any conflict of interest in the couple’s future commercial dealings was not one Buckingham Palace was prepared to take. They also want to avoid as much as possible any criticism of the couple cashing in on their royal heritage.

In a statement on Saturday, Buckingham Palace said the couple had made clear “that everything they do will continue to uphold the values of Her Majesty”.

The duke was holding one-to-one meetings with a number of foreign leaders at the request of the UK government at the London summit. He sat down for talks with Saad-Eddine El Othmani, the prime minister of Morocco, Peter Mutharika, the president of Malawi, and Filipe Nyusi, the president of Mozambique.

Harry chose a dinner for donors to his charity, Sentebale, to speak from the heart on Sunday after 10 days of turmoil following the couple’s bombshell announcement they wanted to “step back’ as frontline royals.

Johnny Hornby, the chairman of Sentebale, said Harry’s royal status did not matter to the charity.

“I don’t think it matters at all. I think he has a kind of unique ability and an aura around him, when he is with children, when he is with any gathering, his passions come over,” he told BBC Radio 4’s Today programme.