The announcement, less than three weeks ago, that King Charles was seeking treatment for a benign enlarged prostate led to widespread praise for what seemed to be a new strategy of royal openness, after decades of discretion, and occasional concealment, regarding the health of Queen Elizabeth.

The king had personally wanted the details of his treatment to be made public, the palace let it be known – in part to encourage other men who might be experiencing symptoms to get checked out. Searches for the condition on the NHS website went up, and the public was assured he would be back at work soon.

But with the discovery, made during his prostate treatment, that the king had an unrelated cancer, that press approach abruptly changed.

A formal statement released at 6pm on Monday revealed that King Charles had cancer, had already begun treatment and was feeling “wholly positive”. But neither the type of cancer – nor, crucially, the king’s condition – were made public.

Given that he has stepped back from public-facing duties, his aides had no option but to be open – up to a point. Long gone are the days when the public can be entirely kept in the dark about the seriousness of a monarch’s illness, as was the case before the death of George VI in 1952, when even the royal family and the king himself were not told how unwell he was.

King Charles had “chosen to share his diagnosis to prevent speculation and in the hope it may assist public understanding for all those around the world who are affected by cancer,” the palace said.

Any hopes of avoiding speculation were in vain. However, despite inevitable calls for the palace to be more open, there is no expectation that the king’s specific condition will be disclosed anytime soon. Neither the palace nor Downing Street would be offering a “running commentary” on his treatment, aides stressed on Tuesday.

Aside from the death of the queen, this is the most serious health announcement the palace has had to handle in the 70 years since George VI’s death, and a particular challenge for a relatively new press team.

It is led by Tobyn Andreae, a former senior Daily Mail editor who was appointed communications secretary immediately after the queen’s death and who has been steering what some see as a more open approach since Charles’s accession.

“The communication around the prostate problem and now this – it’s all [in] keeping with wanting to have a different style, and I think that people around the king have been planning for this change in style for quite a long time,” Simon Lewis, a former palace communications secretary, told the BBC.

“There were episodes when I was at the palace of members of the family being hospitalised and very little was said, and at that time, it seemed absolutely right. Now it doesn’t.”

Steve Double, a partner at crisis communications specialists Alder PR, said the decision to disclose the cancer diagnosis was “entirely sensible”.

“What it won’t do, of course, is to dampen down speculation about the form of cancer and at what stage it is at. I suspect the palace will remain steadfast on not disclosing that. The palace was robust in shooting down some lurid speculation by an overseas broadcaster about the Princess of Wales’s recent hospital stay, so it remains to be seen whether they will be as proactive regarding the king.”

Do we have a right to know the details of the king’s cancer? Some have pointed to the example of the US, where presidents routinely give details of their medical examinations. We know, for instance, that Joe Biden uses a Cpap machine at night to manage sleep apnea.

There is no legal obligation for them to do so, however, and the information may have limited value anyway. Donald Trump’s former personal physician, who in 2015 said he would be “the healthiest individual ever elected to the presidency”, later said the then candidate had dictated the letter for him to sign.

To argue that the monarch has no right to any medical privacy would be unjust, according to Lewis. “I do think the palace has gone as far as it possibly could do in communicating this whilst protecting his privacy.”