His intervention could not have been made at a more politically sensitive time. Ten days ago, the Government sought to reassure the public that GM food and crops were safe; last week Tony Blair accused the media of whipping up "hysteria" over the issue.
The medium through which the heir to the throne chose to express his views was surprising, too. A tabloid newspaper, one that prides itself on its reactionary instincts and anti-intellectualism. And one that consistently sided with his former wife, Diana, Princess of Wales, during the acrimonious breakdown of their marriage.
Three months ago, Richard Kay, the Mail's royal correspondent, approached Prince Charles's private office to convey a request from his editor, Paul Dacre. The Mail, like several other newspapers, had been campaigning against GM food. The Prince was well known for his concerns on the subject. Would he care to write an article for the Mail?
According to insiders, Prince Charles was initially lukewarm. "He took a lot of persuading," said one source.
It was not the prospect of putting his name to an article that bothered the Prince; he had written for various publications, and last year penned a piece on GM food for The Daily Telegraph.
The Telegraph, though, is his natural home, and it supported him during his marital crisis. Its environment editor, Charles Clover, co-wrote a book with him about his organic estate at Highgrove, Gloucestershire.
The Prince's aides were divided, too. Among those opposed to the project was Commander Richard Aylard, the private secretary who encouraged him to confess to adultery in Jonathan Dimbleby's television documentary. Mr Aylard was sacked from the private office, but is retained as an environmental consultant.
Others, especially Stephen Lamport, who replaced Mr Aylard, and Sandy Henney, the Prince's press secretary, urged him to go ahead. As one veteran royal watcher said yesterday: "Things have changed at St James's Palace. They want to be more inclusive, and they realise that it's pointless to exclude the tabloids. The tabloids can be useful and they have a big audience."
In the end, it was the timing that swung it. "The Prince feels very passionate about this issue," said Patrick Holden, director of the Soil Association, the body that regulates organic farming, and one of the experts regularly consulted by the Prince on such matters.
"He feels that if we're going to turn the tide on GM food, we've got to do it now. The Mail is the voice of Middle England, and it has got a big readership, more than two million. I suspect that strategically he felt it was the right place for an article."
Once Prince Charles had agreed to the piece, he began the process of consulting a wide range of advisers, both from within his own office and from the environmental movement.
The latter are understood to have included Mr Holden, Jonathan Porritt, former director of Friends of the Earth, and Shaun Woodward, a Tory MP who farms organically at his Oxfordshire estate and has met the Prince on several occasions.
One of Prince Charles's favourite ways of canvassing views is to invite a group of experts to a brainstorming session, either over tea at St James's Palace or over dinner at Highgrove.
Environmentalists, journalists and politicians have all been invited to such soirees. The Prince has also met Robert Shapiro, chairman of Monsanto, the firm behind the push for GM technology.
"They are quite workmanlike affairs," said a journalist who attended one meeting. "There is not much time wasted in frivolity or idle chitchat."
The material for the Mail article was drawn together by Elizabeth Buchanan, the assistant private secretary with responsibility for environmental matters.
The format was devised because the 10 questions reflected the concerns expressed by thousands of visitors to an Internet site set up by the Prince six months ago.
A fortnight ago, the Mail and St James's Palace agreed that yesterday should be publication day. The Prince was given a draft to rewrite. He completed his reworking of it during an official visit to Nigeria last weekend.
Friends say he thought long and hard before issuing what was, in effect, a direct challenge to the Government. Mr Woodward said: "This is arguably the most important thing that he has done, in media terms, because these are the questions that we ignore at our peril."
Yesterday, back in London, the Prince must have allowed himself a small smile of satisfaction as the Environment minister Michael Meacher told a Sky News programme that he had raised "wholly legitimate questions which indeed the Government welcomes and which the Government is systematically trying to answer".
Who Advised Him?
Commander Richard Aylard
Was the Prince's closest adviser for many years and a man credited with influencing many of his political and social views. The two men found a bond in their concern for the environment and Aylard wrote many of the Prince's speeches on the subject.
When the Prince decided to write a book about his estate, he asked Mr Clover, the environment editor of The Daily Telegraph, to co-author it. The resulting volume, Highgrove: Portrait of an Estate, allowed him to argue the case for organic farming.
The environmentalist and director of the Soil Association was one of the Prince's key consultants when he converted his estate. He is an ardent supporter of the Prince, whom he credited with making organic farming "respectable".
Was warning of potential problems with GM foods before the issue became fashionable. A former Friends of the Earth director and Ecology Party candidate, he has written numerous books on the subject, including Where On Earth Are We Going?
The Prince's private secretary is considered "one of us" by Buckingham Palace's old guard. Before joining the Prince's office in 1993, served in UK mission to the UN and Tehran. Has co-written political thrillers with former foreign secretary Douglas Hurd.
Shaun Woodward MP
Former Tory press chief, he shares the Prince's passion for organic farming: has visited Highgrove for long meetings about it. Has converted part of the farm he shares with his wife - Sainsbury heiress Camilla - to environmentally friendly crops.
CHARLES'S 10 QUESTIONS ANSWERED
Do we need GM food in this country?
Yes - it will provide economic and environmental advantages that could benefit us all
No-one needs or wants GM food or crops except the agrochemicals industry
If it lowers pesticide levels and produces cheaper food with added nutritional benefits - yes
Is GM food safe for us to eat?
Yes The Chief Medical Officer and Chief Scientific Adviser think so; data from the US says so too
Not if we think in terms of the wider damage to the environment, which affects the future health of us all
Present products are, but each new food should be tested for adverse immune reactions and toxicity
Why are the rules for approving GM foods so much less stringent that those for new medicines produced using the
It is not feasible to set the same standards for a new food than to a new drug because food is by its nature an impure substance
Because it was the only way the GM industry could fudge it. GM food would fail the safety tests conducted on new drugs
New foods undergo more rigorous tests than traditional food. Suggesting that clinical trials should take place on GM food is unrealistic
How much do we
really know about the environmental consequences of
Plenty, from the US experience, which began in 1991 It shows no adverse effects
Next to nothing. Limited research has shown potential damage to important animals and plants
There is a need for more research, which is why the British farm trials should go ahead
Is it sensible to plant test crops without strict regulations
You can't plant GM crops without Government permission, and the guidelines are mandatory
No. The trials are for the benefit of Monsanto and the Government and no-one can predict their adverse outcome
The regulations on GM crops are far more stringent than the public is aware of: field trials are the last in a long line
How will consumers be able to exercise genuine choice?
GM food grown in this country will be segregated and labelled
They won't if the farm trials go ahead as contamination is inevitable
Labelling is the key, and has been the undoing of the pro-GM lobby to date
If something goes wrong with a GM crop, who will be
`The polluter pays' - so initially it will be the grower, who can sue suppliers, and so on
All of us will end up paying for the mistakes of a few, just like we did with the BSE crisis
A weak link in the pro-GM lobby. How do you identify who supplied a piece of GM food?
Are GM crops really the only way to
feed the world's
No - you could stop wars and improve distribution But realistically, we'll have GM crops first
Ask the people who live there. They say they want to improve their own farming methods
History shows it is wars and greed which usually cause starvation; GM crops won't change that
What effect will GM crops have on the people of the world's poorest countries?
Real benefits could result from new crops resistant to pests and nutrient enriched - needed in many countries
Relying on the GM industry will make matters worse, making the developing world more dependent
They may feed them while making them dependent on multinationals - but that is already the case to some extent
What sort of world do we want to live in?
One with sustainable agriculture, a balanced environment, and tasty, cheap, safe food. Technology is the catalyst to create that
One not dominated by multinational corporations who put profits before the environment and oppose human independence from corporate greed
One where people make rational decisions based on science, where we accept that not every problem has a simple, technological fixReuse content