The Prince of Wales has been praised by the head of a humanitarian organisation for “keeping calm and carrying on” after testing positive for coronavirus.

David Miliband, president and chief executive of the International Rescue Committee (IRC), also said Charles was “very engaged” with the situation facing the nation after talking to the royal, patron of the IRC’s UK arm, on Wednesday.

The heir to the throne, who is back at his desk working, was said to be “enormously touched” by well-wishers’ kind words after receiving hundreds of get-well messages, the day after it was revealed he had contracted Covid-19.

Mr Miliband told Sky News: “I had a scheduled call with the Prince of Wales yesterday, obviously getting the news in the morning of his coronavirus situation made me wonder whether he would postpone, but he went ahead with the call.

“He was in very good spirits, he was obviously very engaged with the situation facing people in the UK.

The former foreign secretary added: “I was very struck about how he was very concerned about the global picture as well as his first priority being in the UK.”

Mr Miliband went on to say: “So it was very reassuring to hear him keeping calm and carrying on, very determined to make sure that the virus didn’t interrupt his schedule, and continuing to express concern both locally and globally.”

Charles is conducting meetings by phone as he recovers from the virus, and is mirroring other members of the monarchy who are using a combination of video conferencing and calls to carry out royal duties.

Clarence House tweeted: “Thank you for all your ‘Get Well Soon’ messages for His Royal Highness.

“He is enormously touched by your kind words.”

Scotland’s chief medical officer has again defended the decision to test the heir to the throne for coronavirus, saying there were “very good reasons” behind the move.

Charles is self-isolating at his Scottish home Birkhall, in Aberdeenshire, while his wife the Duchess of Cornwall is living separately from her husband in the property after she tested negative for Covid-19.

A Clarence House spokesman declined to give a update on Charles’ health status after it was announced on Wednesday he had tested positive for coronavirus.

But he said the prince was working at his desk as usual and had received hundreds of “get well soon” wishes sent to him at Clarence House – a mixture of cards, but mostly digital messages.

A source said it was “business as usual” for the prince, adding: “The general plan is the prince will continue maintaining a diary of work but it will be done through telephone calls and digital conferencing.

“He is likely to focus on core areas – his Sustainable Markets Council work for the environment, his Prince’s Foundation and Prince’s Trust work.”

Coronavirus graphic
(PA Graphics)

Speaking about Charles on BBC Radio Scotland’s Good Morning Scotland programme, Dr Catherine Calderwood, Scotland’s chief medical officer, said: “I have spoken to the team in Grampian who were looking after the individual.

“My understanding is there were very good reasons for that person and his wife to be tested, and obviously I wouldn’t be able to disclose anything else that I know because of patient confidentiality.”

Some medical workers who are self-isolating have been unable to get tested to see if they could come back to work. Both Charles, 71, and Camilla, 72, were tested on Monday.

Clarence House said on Wednesday that Charles had been displaying “mild symptoms” of the illness but was in good health and spirits.

Charles uses a Namaste gesture at the Prince's Trust awards ceremony to greet television presenters Ant McPartlin (left) and Declan Donnelly during the royal's last public appearance before he contracted coronavirus. Yui Mok/PA Wire
Charles uses a Namaste gesture at the Prince’s Trust awards ceremony to greet television presenters Ant McPartlin and Declan Donnelly (Yui Mok/PA)

A source added “medical advice is that it is unlikely to escalate into a more serious case”.

SNP MSP Joan McAlpine tweeted that she wished Charles a “speedy recovery”, but added: “Given that his symptoms are said to be mild, like many I wonder how he was tested when many NHS and social care workers cannot get tested.

“My nephew, who has serious asthma and a chest infection, was recently refused a test.”

With tourists being urged to stay away from remote areas of Scotland during the outbreak, former SNP MP George Kerevan was more critical, branding Charles an “arrogant fool”.

The prince has been joined by his son the Duke of Cambridge, brother the Earl of Wessex and the Queen in holding usually face-to-face meetings by phone or via the internet.

The Prince of Wales sits opposite Prince Albert of Monaco at the WaterAid charity’s Water and Climate event in London. Albert later tested positive for coronavirus. PA/Wire
The Prince of Wales sits opposite Prince Albert of Monaco at a WaterAid event in London – Albert later tested positive for coronavirus (PA)

William held a meeting on Wednesday by telephone with Mick Clarke, chief executive of the homeless charity The Passage, which the royal supports as patron.

The Evening Standard reported the duke had told Mr Clarke: “We are in a life and death fight to help those people living on the streets in this public health emergency.”

Pictures showing the Queen holding her weekly audience with Prime Minister Boris Johnson by phone were posted on the royal family’s official Twitter account on Wednesday evening.

The Queen, who Buckingham Palace has said is “following the appropriate advice with regard to her welfare”, will be working as normal from Windsor Castle as every day of the year she receives papers of state to read, and some to sign, in famous red boxes.

These are sent up to her by her private secretaries in the red boxes also used by Government ministers to carry confidential documents.

The papers, from Government ministers and from the Queen’s representatives in Commonwealth and foreign countries, are policy papers, Cabinet documents, Foreign Office telegrams, a daily summary of events in Parliament, letters and other state documents.

Edward, who is a trustee of the Duke of Edinburgh’s Award, took part in a video conference on Tuesday in his role with the organisation started by his father.