Even before her husband the king received his diagnosis, Queen Camilla had been showing support to many people living with cancer.

She has been president of the cancer support charity Maggie’s for more than 15 years and frequently talks to patients and staff at their facilities, most recently last Wednesday, when she opened a new centre at the Royal Free hospital in London. As we now know, she had already been told about her husband’s illness.

The following day she was greeted by schoolchildren in Bath, visited a set of almshouses and attended a commemorative service for the St John’s foundation at Bath Abbey.

On Friday she was in Cambridge, visiting a community centre where she was introduced to Strictly Come Dancing’s Johannes Radebe, and Tasha Ghouri from Love Island, joking with the latter that she had not watched the programme, “but my children have”.

It’s an unrelenting schedule for a woman of 76 – the queen carried out 233 royal engagements last year, and there will be many more while the king is out of action.

Her husband may be stepping back from public-facing duties while he is having treatment, but the queen will continue with her full programme of activities, Buckingham Palace has said.

Less than 18 months after becoming queen, the woman who was once viewed as a threat to the monarchy now finds herself having to assume much of the responsibility for keeping the royal show on the road.

Inevitably, much of that burden will also fall on Prince William, who has scrambled back to royal duties this week, but with the Princess of Wales still out of action while she recovers from abdominal surgery, Queen Camilla’s role has never been more central.

For a woman who enjoys a no-nonsense reputation, and was once described by her husband as “jolly good and down to earth”, it will doubtless be a matter of keeping calm and carrying on.

Camilla has admitted in the past, however, that she finds her schedule punishing, telling the wife of the Sultan in Brunei in 2017 that her duties were “very tiring. Every day, we’re non-stop. It’s more tiring as you get older. I keep trying to tell everybody that I’m not as young as I used to be, and have to slow down.”

She has had health concerns of her own, having undergone a hysterectomy, suffered a broken leg and broken toe, and struggled with repeated bouts of sinusitis.

“This will add extra stress to her,” says the royal commentator and former BBC correspondent Peter Hunt. “Her health has not been as robust as his up until this point. She has adjusted remarkably well, when you think that it’s only in the last few decades she’s actually been on the royal scene.

“She is now the queen and she will have to balance the two issues of responding to his needs as his partner and the demands of being the most senior royal.

“Collectively across the palaces, they are going to have to look at their diaries and work out – can they cover all the events there are demands for, or are they going to have to reduce them?”

It is a “moment of stress” for the institution, he says, “because they probably don’t have a clear idea in terms of a timeframe of when he will resume public duties”.

The queen is patron or president of more than 90 organisations, and the royal mantra will remain that neither she nor any other member of the family wants to “let them down” by cancelling or postponing events.

The king may be skipping engagements, but anything that is constitutionally important, such as attending to state documents and his daily government red boxes, he will continue to handle from home, say aides.

However tempting it might be for the queen to join him there, her ongoing visibility is extremely important to the royal family, says Hunt.

“It is pretty well accepted within the institution that the mantra of the king’s mother still holds, which is: you have to be seen to be believed. So in his absence, who steps up to do that work? There aren’t as many of them as there once were.”