The event followed a day of meetings for the prime ministers and presidents attending the UK-Africa Investment Summit in London.

Prince Harry was present at the summit earlier in the day but missed the reception and has since flown back to Canada to be with his wife Meghan and their son Archie.

It was the first event William and Kate have hosted since the Duke and Duchess of Sussex announced they would be stepping back from royal duties.

Also at the event were the Earl and Countess of Wessex and the Princess Royal, who mingled with the heads of state and government and their partners, Boris Johnson and UK and African business figures.

It was claimed today the Queen and Prince Charles decided to let the Sussexes keep their titles because they did not want to seem ‘petty’ and remove them.

Harry and Meghan retained their HRH titles, which they will not use commercially, and their Duke and Duchess monikers.

A source told the Evening Standard the Queen considered calling the Sussexes the Earl and Countess of Dumbarton.

This would have made them equal to the Earl and Countess of Wessex, Edward and Sophie.

A source told the newspaper: ‘The Sussex title is one of the ancient royal dukedoms given to him ahead of his wedding to Meghan, along with other titles.

‘Removing it was seriously considered and discussed at the highest level.’

Harry gave an emotional speech on Sunday night where he told the ‘truth’ 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.

Earlier today, the Duke of Sussex carried out what is likely to be one of his few remaining official engagements when he met some of the leaders for audiences – one-to-one meetings.

The Prime Minister and the duke had an informal ‘catch-up’ chat, meeting for 20 minutes one-to-one without any aides present.