The King’s openness about his cancer diagnosis contrasts significantly from how the news of his grandfather’s ill health was handled.

On February 6 1952, this day 72 years ago, King George VI died in the middle of the night.

He had survived a major operation to remove his left lung in September 1951, but succumbed to a blood clot just a few months later.

It caused a coronary thrombosis, the blockage of the coronary arteries that carry blood to the heart, leading to a sudden collapse and fatal heart failure.

His death came as a shock to the public and the royal family, as even the King was not informed of the full extent of his illness.

He had waved goodbye to his 25-year-old daughter and heiress, Elizabeth, just a few weeks before as she left to visit Kenya.

News of her father’s death, and her immediate accession to the throne, reached the Queen while she was on safari.

Since then, the medical profession – and the royal family – have changed.

Speaking to BBC Radio 4’s Today programme on Tuesday, former royal press secretary Simon Lewis said that Charles’ openness about his cancer diagnosis has been his “style” as a monarch.

“I think it’s actually been the style of the King’s first year,” he said.

“This is obviously one element of it. But if you think of the book and the access that was given to Robert Hardman, if you think of the documentary, if you think of his whole style as King, I think this is very much in keeping with that.

“And I do think his advisors, with this statement I’m sure we’ll talk about it, have actually got it spot on.

“I think 20 years ago we would have got a very abrupt, short, statement, and that’s about it. And I think they’ve gone as far as they possibly can given that the King has had a diagnosis of cancer and, as a lot of people know, processing that is a pretty tough process.”

Mr Lewis said it was “not so much the crisis itself, it’s how you handle the crisis” that defines it.

“In this case, what could have been a crisis, has now been put firmly in context.

“I think he can go about his working life in the knowledge that people have an understanding that he’s having this treatment as well.

“As I say, so many people around the country are having this kind of treatment. There are so many people who want to continue their working lives whilst being treated for cancer.

“I think it’s a very, very positive message.”

Daily Mail royal correspondent Robert Hardman told the Today programme there was a “great significance” to the King being so transparent about his health.

“I think where we are now is, we’ll say so much, but it’s all about precedent,” he said.

“If you set a precedent of giving away all the details, all of the time, immediately, for any patient that can be troubling.

“I think they are going to want to let information out as and when it feels appropriate.

“There’s a sense that we’ve been open enough thus far, if you need to know more you will.

“That’s where we’re standing for now. We want to hold something back, because everybody does.”