Camilla: "I do love you and I'm so proud of you."

Charles: "Oh, I'm so proud of you."

Camilla: "Don't be so silly, I've never achieved anything."

Charles: "Yes you have."

Camilla: "No I haven't."

Charles: "Your great achievement is to love me."

Camilla: "Oh, darling. Easier than falling off a chair."

Charles: "You suffer all these indignities and tortures and calumnies."

Camilla: "Oh, darling, don't be so silly. I'd suffer anything for you. That's love. It's the strength of love."

Extract from the "Camillagate" tape, recorded at approximately 1am, 18 December, 1989

On the evening of 18 July last year, there was a surprise in store for the hack pack waiting outside Highgrove. It was the venue for a party thrown by Prince Charles to celebrate the 50th birthday of his very good friend Camilla Parker Bowles and the snappers were out in force. But there was to be none of the usual scrummaging for a snatched shot of the chief guest. "If you want to see the main shot, boys, just stay here," said the helpful police inspector on duty. It was almost unheard of.

And there were more surprises to come when the main shot approached, in the form of a Ford Mondeo carrying Mrs Parker Bowles. The car actually slowed down, enabling the snappers to get a good long look. Mrs Parker Bowles was wearing a figure-hugging black gown. Around her neck was a diamond and pearl necklace and on her lips was the smile of a woman who seemed to sense that finally her time might have come.

"Camilla's a Thriller", ran the headline in the next day's Mirror. The tide was turning at last. Two weeks previously, Channel 5 had broadcast a largely sympathetic 50-minute documentary about Mrs Parker Bowles's life. And only hours before her appearance at Highgrove, Tony Wright MP, Parliamentary Private Secretary to the Lord Chancellor, Lord Irvine, had sent out a clear signal that there was government support for the idea of a marriage between Mrs Parker Bowles and Prince Charles. "Most people in this country would rather have a happy monarch than an unhappy monarch, and I certainly would," he had told the BBC, adding that the Church could face disestablishment if it tried to stand in the way of their union. The future was indeed looking bright for the woman who had long played the unwelcome role of Wicked Witch opposite Princess Diana's Good Fairy.

There were to be happy endings all round that summer, it seemed. As Diana gambolled in the Mediterranean a few weeks later with Dodi Fayed, an article appeared in the New Yorker in which Charles's close friend Patti Palmer- Tomkinson talked openly of his relationship with Mrs Parker Bowles. She described a couple happy to simply potter together in the garden. "You know, after all these years," she said, "they're just happy to breathe the same air."

It was widely expected that their first public outing would come in September, when Mrs Parker Bowles was due to host a glittering pounds 100-a-head charity bash on behalf of the National Osteoporosis Society, of which she is a patron. It was even mooted that the couple might go on holiday together. The years of concealment and deceit would soon be gone for good.

And then with a screech of tyres in a Paris underpass, everything changed, and Mrs Parker Bowles was once more consigned to the darkness. The charity bash was immediately cancelled and the curtains at her Wiltshire home remained drawn. "Diana's death has set Charles and Camilla back years," commented Judy Wade, royal correspondent of Hello! magazine, echoing the general consensus of royal commentators. "It is the worst thing that could possibly have happened to them. Their situation is absolutely hopeless. If Camilla's car is seen near Highgrove in the next six months, it could be the end of them. The public simply won't tolerate it."

So Mrs Parker Bowles stayed at home. But unfortunately she couldn't stay out of the newspapers. At the beginning of October, a familiar skeleton was dragged from the closet as the new version of Andrew Morton's book Diana: Her True Story hit the bookshops. The original had revealed Charles's relationship with Mrs Parker Bowles for the first time, and now the updated version contained transcripts of tapes recorded by Diana in which she spoke of meeting her husband's lover. She described how she asked her to sit down, then told her, "Camilla, I would just like you to know that I know exactly what is going on between you and Charles ... Don't treat me like an idiot." The transcripts also revealed that the affair had caused bitter arguments - "rage, rage, rage" - between Charles and Diana. As her friends sought to stress that Diana's attitude to her had softened in the final months of her life, Mrs Parker Bowles maintained a dignified silence, as indeed she always has.

By November, Mrs Parker Bowles was to be seen in public, riding with the Beaufort Hunt. Charles was observed doing the same, but the couple made sure they were never spotted together. "They have been following this pattern for some time," a "source close to the hunt" told the Daily Mail in December. "She goes out, then he goes out. She comes back and he stays out riding, often until it's dark."

But behind the scenes and far from the public gaze, things were different. In March this year, the first ray of light was shone on the couple's clandestine arrangements when it was revealed that Mrs Parker Bowles regularly stayed the night at St James's Palace, Charles's London home. She was said to stay there up to three times a month, although she kept no possessions there and was never present when Princes William and Harry were visiting their father. "They are both aware their relationship is sensitive and can cause upset if publicly flaunted," a "pal" of the couple told the Sun. Less than two weeks later came the further revelation that Mrs Parker Bowles had been Charles's guest at a weekend party at Sandringham. The occasion was a "highbrow weekend" of culture and reflection to which the great and the good had been invited, and the guest list included Lord Rothschild, the playwright Peter Whelan, the author Piers Paul Read and the director of the Tate Gallery, Nicholas Serota. However, the main talking point was the presence of Peter Mandelson and the possibility that the couple might be taking advantage of his spin-doctoring talents.

The question had been raised before. In his book Blair's Hundred Days, Mandelson's former aide Derek Draper alleged that Mandelson had had several meetings with Mrs Parker Bowles to discuss the issue of her marrying Charles, although the claim was dismissed outright by Mandelson's current staff.

"He takes an interest," a royal aide told me. "He rather likes her. It's no secret they've met from time to time but it's always been social. I think she's flattered he took an interest. Nobody else who mattered ever had. The last government never took any interest in these things or sought to be helpful. He's quite supportive of her, which is nice."

With the coming of spring, Mrs Parker Bowles's self-imposed solitary confinement seemed to be coming to an end. In May, she made her first high-profile public appearance since Diana's death when she attended the wedding of her godson, Henry Dent-Brocklehurst. The press noted the fact but on this occasion were more concerned with the sight of Liz Hurley's sequinned leopard-print knickers. In June, she appeared with her son Tom, Charles's godchild, at Sir David Frost's annual garden party. "In an attractive pink tweed suit and pearls with a smile to match, 50-year-old Camilla was clearly trying to soften her public image as the woman blamed for helping to wreck a fairy-tale royal marriage," said the Mirror, somewhat crassly.

At the beginning of July came the real shocker when the Sun revealed that Mrs Parker Bowles had met Prince William at St James's Palace. It was a purely chance encounter, the newspaper reported, the young Prince having dropped by to change his clothes. The meeting lasted no more than 20 minutes and sensitive subjects were avoided. Afterwards Mrs Parker Bowles was said to have needed a stiff gin and tonic.

When the story emerged, it was seen by many as the latest move in a deliberate campaign by Prince Charles's private office to garner public acceptance for Mrs Parker Bowles. His office, however, strongly denies it.

"There is no campaign," a senior aide told me. "All that she does - and it's very much her decision, because she's very much her own person - is try to keep out of the public gaze as much as possible. She obviously does things with the Prince of Wales when he's in his private time, because she is very much part of his private life, and yes, those things do get out, and it's often rather terrifying how quickly they get out. Sandringham leaks like a sieve. They would be naive if they thought they could do these things and it wouldn't get out. And they're not naive."

In the case of the Prince William story, an investigation by Palace staff revealed that Mrs Parker Bowles's personal assistant, Amanda MacManus, had mentioned the meeting to her husband, an executive at the Times, who had then apparently told somebody else who then informed the Sun. As a result, Mrs MacManus, who, on her appointment last August, told the Mail, "I can be discreet," handed in her resignation.

"It needed to be cleared up because there were a lot of people saying we were selling Prince William's privacy to buy brownie points for Mrs Parker Bowles," says the aide. "Which is why we were so determined to get to the bottom of where it had come from. Fortunately there was someone with the decency to own up, which rarely happens in these circumstances. I think everybody knew it would come out eventually, but not quite so quickly and not in isolation like that."

The reason they knew it would come out was because William had invited Mrs Parker Bowles to an early 50th birthday party for Charles at the beginning of August. When the day came, once again the snappers were out in force, but with less luck. This time, special arrangements had been made to keep them away from her. "It wasn't her party and Camilla didn't want to be seen as the star attraction," says the aide. "She just said, `Get me in without the cameras, please.' "

When the anniversary of Diana's death has passed, attention will begin to focus on Charles's 50th birthday in November. Speculation is already mounting as to whether the Queen will invite Mrs Parker Bowles to the party she will be hosting at Buckingham Palace. This, however, is dismissed as "complete crap" by his office. "There is a commentator-invented expectation that there is going to be some sort of great roll-out at his birthday, that she'll pop out of a cake arm-in-arm with him and this will be the great coming-out, which is not true at all," says a Palace spokesman. "There's all sorts of expectation that they'll be seen together at something, but if ever there is an appearance together it will be by chance and I think it will take everybody by surprise."

The question of a wedding is also given short shrift at St James's Palace. "The last thing he said about it was two years ago and he said he had no intention of getting married," says an aide. "Their relationship has changed a lot in the last few years since he got divorced, because they actually spend some proper time together. There's a degree of normality that's entered their lives. She comes to London, she stays in London, they go out in London from time to time. They've never been seen together in London but they go out together to dinner with friends and to private parties. It's all done very carefully, discreetly and quietly, but it happens. And from their point of view that's made quite a difference to their ability to get on with their own lives together."

Another view is expressed by the author Anthony Holden, whose new biography of Charles is due to be published this autumn. He believes that Mrs Parker Bowles wants to marry, and although Charles may want the status quo to continue, he will soon find himself in an impossible position.

"The story of the autumn as it builds up to his birthday will be `Will he or won't he?'" says Holden. "I think his problem really is with the bedrock monarchists, who don't like him having an open relationship with somebody who is not his wife. He's got to regularise the relationship one way or the other. If he thinks he can't have both and puts the throne first and dumps Camilla, then he will be perceived to have ruined her life as well as Diana's. The easiest get-out for him is to marry her. Public opinion may cause a fuss at the time, but his mother's going to live for another 20 or 25 years, so there's plenty of time for people to get used to it, and I'm sure in the long term it would not be a problem."

Indeed public opinion is already softening. In a recent Guardian/ICM poll, the percentage of those who felt that Charles should marry Mrs Parker Bowles had risen from 30 to 35 per cent since last October. Less than half were now opposed to the union.

Mrs Parker Bowles is a nice woman, everyone who's met her agrees, a decent sort, very steady, very sensible, just what Charles needs. And throughout all the indignities and tortures and calumnies, she's shown remarkable resilience and considerable dignity. Charles was probably right when he said that her great achievement was to love him

The never-ending story

December 1997: Diana's squirrels drowned

Royal gardeners spark public outrage after being implicated in the disappearance of dozens of squirrels in Kensington Palace's grounds. Up to 50 are drowned in the palace ponds because royal aides fear an infestation. The Princess, it is said, used to leave out nuts and crumbs for the animals, which were apparently a favourite with the young princes.TV presenter and animal-lover Rolf Harris calls the cull "horrific".

January 1998: Stores veto scratchcards

Leading supermarkets including Tesco, Sainsbury's and Asda opt not to sell a pounds 1 scratchcard featuring Diana's signature in her favourite purple on a rose because it is an "inappropriate" way of raising cash. The scheme, which has a pounds 25,000 top prize for punters, is branded vulgar by some critics, but other shops, petrol stations and 9,000 post offices agreed to sell the cards. MP Peter Luff calls the scheme "crass exploitation"

February: Student's `sick' jokes

A student magazine sparks fury when it prints a page of gags about the death of Diana. The content of PTQ, published by the Rag committee at Queen's University in Belfast, is branded "a joke too far" by a university Senate member Peter Weir. He said: "A lot of people are still distressed by Diana's death, and this is in very poor taste. It's sickening."

March: She should have worn a seat belt

The RAC seeks approval from Buckingham Palace for a television and poster campaign claiming that Diana would have lived had she worn her seat-belt in last year's road crash. A spokesman for the RAC says, "It's an obvious example of how there could be a positive outcome from Diana's death." Others object to the campaign, among them Tory MP Ann Widdecombe. She says: "Do the Princes really want to see all over the place 'Your mum would have lived if she'd had a seatbelt on'?"

April: Diana's signature for pounds 10,000

In an American magazine, a specialist autograph firm Fraser's advertises for sale an accident report form which Diana purportedly filled in when she was 19 years old - for pounds 10,000. The advert proclaims: "This is a truly magnificent piece from a woman who touched the hearts of the world and whose tragic death continues to shock us all." Friends of the Princess condemn the offer as tasteless.

May: Peeping builders

Two workmen are sacked after smoking dope and trying to sneak a look at Diana's island grave. The two peeping builders working on the Diana museum at Althorp are caught in the lake and fired on the spot. One contractor comments: "It's well-known what's been going on. People have been trying to swim to the grave. For lads who have had a bit of a drink, it's the obvious jape." A source at the site says: "Everyone has been warned to stay away from the lake. If anyone goes down there they'll be on their way out."