To tie or not to tie? For the Prince of Wales, such considerations are normally never an issue, because wearing a tie is simply what he does. But yesterday he was addressing Google’s annual Zeitgeist conference, where movers and shakers go to discuss the big ideas of the day and, as a rule, do not wear ties.

The first hint that he might not have got the dress code quite right came when he arrived at the Hertfordshire hotel, where he was giving a talk on Meeting the Challenges of the 21st Century, and was introduced to a tribal chief from the Amazonian rainforest, who was not just not wearing a tie, but had a feathered headdress.

Then the Prince walked into the conference hall, where he found himself surrounded by business leaders, politicians, technocrats, media folk and a scattering of European royalty. And half of them were not wearing ties.

“I had not quite appreciated that this was a theatre-in-the-round experience,” he said. “I feel rather overdressed. I might take my tie off.” This was a joke, of course, the Prince of Wales would as likely take his tie off as he would power up a chainsaw and start chopping down the rainforest.

Until recently the world assumed that the Prince scarcely knew what the internet was. Not any more: this invitation, and the launch of the Prince’s rainforest video on MySpace, has revealed that he is almost as media-savvy as his mother, 83. “I am very touched that Google should have asked me to speak at what has become a most prestigious annual conference,” he said. Other participants included Larry Page, the Google founder, Sir Richard Branson, George Osborne, the Shadow Chancellor, and James Harding, Editor of The Times.

“The great thing about Google,” the Prince said, “is that as I get older and forget who I am and where I live, I can just press a button and remind myself instantly and from a bird’s-eye perspective.” This was clearly a joke, too.

The Prince’s message was that with the world facing an environmental crisis as well as an economic one, it could no longer be a question of seeing the development of the world economy and the protection of the environment as choices.

He then visited the eco-home in Watford designed by his Foundation for the Built Environment. There, in a hard hat and hi-visibility waistcoat, he laid one of the clay blocks that form the basis of the house. He managed to get a line of cement on to his trousers, prompting him to exclaim, “Does this come off?”, which just goes to show that when you are the Prince of Wales, choosing the right clothes for a day’s work is a lot harder than it looks.