Kate's cancer struggle is even front- page news in Ecuador, says historian IAN LLOYD. Popularity is one thing, but what sort of monster have we unleashed?

After a professional lifetime of watching the British Royal Family, first as a professional photographer and now as a historian, I've got a pretty good grasp of how the media coverage works, the incessant nature of it, and so on.

That, at least, is what I thought - until the health struggles of King Charles and, more particularly, Catherine, the Princess of Wales.

The world-wide attention is on a scale I've never seen before, with the possible exception of the coverage devoted to Diana amid the dramatic collapse of her marriage to Charles.

In the wake  of Kate’s moving video message, in which she revealed her cancer diagnosis, I looked at the coverage in overseas newspapers - and the results surprised even me.

An image from Catherine's powerful video address, in which she told the world of her cancer diagnosis

King Charles is undergoing cancer treatment. Here, he is pictured with Queen Camilla at Sandringham last month

It was not the first time we have seen the Princess of Wales alone on a bench. Here Diana poses outside the Taj Mahal on a 1992 visit to India as her marriage was collapsing

The video was given front-page billing in Argentina, Ecuador, Brazil, and Uruguay. 

It also appeared further north in Mexico, Costa Rico, and Honduras.

In the Middle East it was reported in Israel, Egypt, and the United Arab Emirates and in the Far East in Japan, Singapore and Malaysia.

And that is quite aside from the big headlines it attracted in Commonwealth countries, as you might expect, and in most of Western Europe including France, Germany, Spain, Belgium and Switzerland.

Why? Undoubtedly the drama of the video announcement, a bolt from the blue, made a difference. 

There has also been a determination on the part of the royals to appear 'relatable', more open, less stuffy.

Even so, the scale of the interest in Catherine must surely have gone beyond what even their advisers would have expected. 

These are uncharted waters - and it is no wonder the Waleses are concerned 

Previous generations of royalty went to enormous lengths to protect their privacy, of course. 

The true extent of George VI’s battle with cancer was kept, not just from the public, but from his family and even the king himself. 

The unusual good health of Elizabeth II throughout most of her life meant such revelations were unnecessary in her case. For many decades, the Windsors' luck was in. 

Traditionally it has been royal births, marriages, deaths and the pageantry of jubilees or coronations that gets such global coverage. 

Kate’s health battle has in a sense replaced those traditional stories, allowing us to connect with the royals on a personal level.

The princess did right to speak from the heart in my view. It would be interesting to know how she was advised, and by whom.

But I sense she had little choice, and not just because the broadcast was a good chance to put absurd conspiracy theories to rest. But because the world has changed - and continues to change. 

Public expectations are different.

Both and Charles and William will be very much aware of the dangers posed by failing to speak out. 

The Monarchy is still haunted by its mishandling the public reaction to the death of Diana died in 1997. 

The late Queen fell back on protocol and tradition, failing respond as the people wished. 

There is now a demand for 'authenticity', for displays of feeling, which has only increased since then, thanks in no small measure to the power social media.

The princess's moving broadcast met such expectations to perfection. 

If a cancer diagnosis is  distressing to any family, it was all the more of a shock in the case of a relatively young woman, still only 42, with what has always seemed a strong constitution. 

Looking pale and tired, her video was a study in vulnerability - of a sort with which millions around the world can sympathise.

Catherine's cancer diagnosis leads the news in Portugal 

King Charles, too, has received prominent foreign coverage, including here in Spanish daily newspaper ABC

Commonwealth countries showed the interest you might expect. Here The Australian Sunday Times features the video on its front page

There is another Diana link, no doubt coincidental, in how Kate was pictured sitting alone on a bench. 

It brought to mind that famous image of Diana in front of the Taj Mahal during the Waleses ill-fated visit to India in 1992 as their marriage was collapsing. 

Two princess alone amid very personal crises.

King Charles, too, is harnessing the power of empathy. 

His unexpected walkabout at Windsor on Easter Sunday made a positive visual statement, the more so as he was among his subjects rather than in a more formal setting. 

This too appeared in newspapers across the globe with coverage in Spain, Peru, Argentina, Sweden, and the UAE as well as in most Commonwealth countries.

There's an enduring fascination with royalty, as the coverage of both King and Princess show.

This  Croatian front page used an image of the princess looking tired and drawn

Theirs is also a family story, another important point of connection with the nation and beyond.   

But in the decision to share some details of their  health battles, the King and his daughter-in-law are showing a more human side to the monarchy, one in tune with the emotionally expressive times we live in.

But if, as I believe, they have little choice in this, just what sort of monster has been unleashed - and how much more will it expect?

These are hard questions for the Waleses and their advisers in the coming weeks and months. 

Ian Lloyd @IanLloydRoyal