Prince Philip, husband of Queen Elizabeth II, has joked he "can't stand up much longer" in his first appearance since announcing his looming retirement.
The 95-year-old will be stepping down from public life from the northern hemisphere's autumn.
The announcement was made by the Buckingham Palace after an "emergency meeting" was called early on Thursday morning (local time), which was leaked by the Daily Mail.
It sparked speculation as to what the meeting would be about, including rumours either Queen Elizabeth or Prince Philip had died overnight.
When contacted by Newshub, the Buckingham Palace denied those reports, saying both were "alive and well".
In a statement on Thursday morning, the Palace said Prince Philip had decided to step down from public engagements from the northern hemisphere's autumn.
"In taking this decision, the Duke [of Edinburgh] has the full support of the Queen," it said.
He will continue attending events between now and August which have already been scheduled but won't be accepting new invitations, "although he may still choose to attend certain public events from time to time".
At a reception for members of the Order of Merit at St James' Palace, mathematician Sir Michael Atiyah said to Prince Philip, "I'm sorry to hear you’re standing down."
"Well, I can't stand up much longer," he replied.
Prince Philip's most recent public outing before that was opening a new stand at the Lord's Cricket Ground.
The Palace said the Prince would still be associated with the more than 780 organisations he's a patron, president or member of, but won't be playing an active role by attending engagements.
"Her Majesty will continue to carry out a full programme of official engagements with the support of members of the Royal Family," it said.
UK Prime Minister Theresa May, who met with the Queen on Wednesday, paid tribute to Prince Philip's "steadfast support" of Her Majesty and his patronage of hundreds of charities on Thursday morning.
"On behalf of the whole country, I want to offer our deepest gratitude and good wishes to His Royal Highness the Duke of Edinburgh following today's announcement that he will stand down from public duties in the autumn," she said in a statement.