A caption alongside the images read: “Thank you Prince Harry for choosing Tower Bridge Studios! It was an absolute pleasure to have you in our studios and signing our wall we look forward to welcoming your back again.”

No further details of Harry’s visit have been released. Earlier on Monday, Buckingham Palace revealed that the King had issued clarification on the Sussex’s role following their move back to the UK. He instructed his most senior official, the Lord Chamberlain, to write to government departments and the military stating that the former working royals are private citizens.

The strongly-worded letter, a copy of which was sent to the Duke and Duchess, confirmed that their HRH titles remain in abeyance – which means that they will not be used in any official capacity.

It also asks that any security queries should be directed to individual police forces, rather than to Buckingham Palace.

The letter states: “Following the decision by the Duke and Duchess of Sussex to relocate to the UK, we have received a number of requests for guidance. To help avoid doubt or confusion, The King has directed that the following information be shared.

“It is well known that in January 2020 the Duke and Duchess stepped down from undertaking representative duties on behalf of The Sovereign, and are no longer working Members of The Royal Family.

“This position, distinct from the State and Royal duties undertaken by the working Royal Family, and with the personal latitude it brings the couple in respect of financial independence and protection of their privacy as they would wish, will continue to be fully respected.”

It is understood that clarity about Harry and Meghan’s position had been sought at senior Government level, prompting the King to instruct his most senior official, the Lord Chamberlain, to pen the letter and send it to government departments.