The Duke of Sussex and Mr Johnson met for an ‘informal catch-up’ behind closed doors at the UK-Africa Investment Summit in London’s Docklands.

Prince Harry also met with other world leaders, just hours after saying he had ‘no other option’ but to step back from royal life.

Harry carried out what is likely to be one of his few remaining official engagements before the Sussexes take a ‘leap of faith’ and leave the monarchy for a new life in Canada, with the freedom to take on commercial ventures.

Looking relaxed and wearing a suit, shirt and tie the duke arrived at the Docklands where Mr Johnson was hosting the global event.

The Prime Minister and Prince Harry spoke for about 20 minutes without any aides present.

It comes after Harry gave an emotional speech on Sunday night where he gave his side of the story about leaving royal duties behind in a bid for a ‘more peaceful life’ for his family.

His comments came after Buckingham Palace released the outcome of talks between the Queen, Prince of Wales, Duke of Cambridge and Harry over the future role of the Sussexes.

Harry and Meghan had wanted to remain as working royals, although not prominent members, and drop their public funding so they could become financially independent – a dual role many commentators said was fraught with problems.

But in a statement issued on Saturday after royal family talks concluded, the Sussexes announced they will stop carrying out royal duties from the spring, no longer use HRH and will repay the taxpayers’ millions spent on their Berkshire home.

Critics have accused the couple of turning their backs on the monarchy in order to enjoy the freedom that being able to take on commercial ventures brings.

During the talks between senior royals, all options were reported to be on the table and the Evening Standard has reported the Queen had the choice of stripping Harry of his dukedom and using one of his lesser titles.

In a speech at a private event for his charity Sentebale on Sunday night in London, Harry told invited guests: ‘What I want to make clear is we’re not walking away, and we certainly aren’t walking away from you.

‘Our hope was to continue serving the Queen, the Commonwealth, and my military associations, but without public funding. Unfortunately, that wasn’t possible.

‘I’ve accepted this, knowing that it doesn’t change who I am or how committed I am.

‘But I hope that helps you understand what it had to come to, that I would step my family back from all I have ever known, to take a step forward into what I hope can be a more peaceful life.’

The duke was not officially attending the summit today but was holding audiences – one-to-one meetings – with a number of foreign leaders at the request of the UK Government.

Harry sat down to talks with Saad-Eddine El Othmani, prime minister of Morocco, Peter Mutharika, president of Malawi and Filipe Nyusi, president of Mozambique.