Boris Johnson has been pictured holding his weekly audience with the Queen on telephone in response to the coronavirus outbreak.
The social distancing measure came hours after it was revealed Prince Charles had become the highest profile case in the UK.
The images of the prime minister and the monarch were released on the royal family’s official Twitter account.
The Queen is pictured using an old-fashioned phone in a sitting room, adorned with ornaments including a china corgi.
The royal family has tweeted: “The Queen held her weekly Audience with the Prime Minister today by telephone. Her Majesty – pictured this evening at Windsor Castle – has held a weekly Audience with her Prime Minister throughout her reign.”
The Queen also had her weekly audience with Johnson by phone last week.
On Wednesdays, the Queen holds an audience with the prime minister in the evening following PM’s Questions in the House of Commons.
This can vary if either the Queen or the prime minister are away.
The day will either be changed or they speak on the telephone.
Members of the royal family have moved over to holding meetings by telephone as the coronavirus crisis deepens.
Charles, the Duke of Cambridge and the Earl of Wessex have all participated in telephone meetings or video conferences over the past couple of days.
The Queen is expected to make a public address to the nation at some point in the coming weeks and is likely to pay tribute to health workers treating the sick, sympathise with bereaved families and offer support to the nation living with the restrictions aimed at combating the virus.
Buckingham Palace said the Queen, 93, who is staying at Windsor Castle with Philip, 98, remains in good health and is following all appropriate advice.
A Buckingham Palace spokeswoman said: “Her majesty the Queen remains in good health.
“The Queen last saw the Prince of Wales briefly after the investiture on the morning of March 12 and is following all the appropriate advice with regard to her welfare.”
Charles, 71, is displaying “mild symptoms” of the Covid-19 illness but is in good health and spirits as he self-isolates at Birkhall in Scotland, a spokesman said.
A source added “medical advice is that it is unlikely to escalate into a more serious case”.
The Duchess of Cornwall, 72, who is also at Birkhall, in Aberdeenshire, has tested negative for the virus, so is separating herself from the prince.
Charles’ office Clarence House said the prince and duchess were tested on the NHS as “they met the criteria required for testing”.
The prince fell ill over the weekend and a source said his doctor’s most conservative estimate was that he was contagious on March 13.