THE dazzling face and figure of Diana, Princess of Wales graces the large screen on the wall. She looks past the camera and flashes a smile to a sea of gawping admirers. I stand and stare at her too, captivated by her screen charisma, her sensational dresses, her beautiful smile.

Image after image follows. Diana the shy bride who can't bring herself to look at the cameras, Diana-the-dutiful-wife holding Prince Charles' hand, Diana-the-stately-princess on a tour of Africa, Diana-the-mother at Alton Towers on the wet 'n' wild rollercoaster with her boys.

If she hadn't died in the Paris under-pass on the morning of September 1, 1997, Diana would probably have been in another stunning dress on her birthday tomorrow, being photographed by the world's press and flashing beautiful smiles at the door of another glittering venue. She might even have had a few wrinkles by now and maybe even given into a slight middle-aged spread.

But she didn't survive the crash and these screen images are all we have. Like a modern day, aristocratic version of Marilyn Monroe or James Dean, the Diana we know and love will always be young, beautiful, gracious.

And for those who couldn't get enough of her in life, Althorp is a dream. The Diana exhibition, organised by The Diana, Princess of Wales Memorial Fund, which opens to coincide with her birthday, shows us the minutiae of her life.

Peering uncomfortably at the exhibits, I feel like a voyeur, digesting the treasured possessions of her life with no greater emotion than curiosity. I stare at all the intimate little objects set on stands behind the glass. There's a pre-marriage diary and entries are written in her familiar bubble writing - "write to the Queen today, 'A' walked past without waving, went to the Ritz with Prince Charles and wore a new dress with diamond earings".

I peer at objects in fascination, partly because they are strangely familiar because they belonged to Britain's most photographed princess. There's an ordinary blue, old-style passport with her name inscribed on it, a series of pictures of beloved pets. There's a child's typewriter on display along with tiny ballet shoes and a battered old teddy.

In some ways, these could be the material remains of any ordinary woman. But, in other ways, they couldn't be. Her famous wedding dress sits behind a screen, her sequinned shoes and exquisite tiara glint with diamonds.

There are roomfuls of condolence books with dimmed lights and a powerful floral smell emanating from heaps of flowers that were left for Diana at the gates of Kensington Palace. You can even catch a posthumous glimpse of her stately funeral. Words from Elton John's Candle in the Wind lie behind the glass, a musical score from her favourite hymn, even the Order of Service at the funeral.

A childhood room has a home video which her father made of Diana at Althorp. She's swimming, posing, laughing and disco dancing to the backdrop of evocative violin music.

For all its touching detail, there is a palatable air of sentimentality running through the stables-turned-showrooms - the shop is selling pink love hearts to mark the estate on which the beautiful Queen of Hearts grew up.

With the exhibition firmly in place from tomorrow until the end of August, Diana has becoming a fairy-tale princess. Her army of fans can view the room she liked to stay in with paintings of children all around and a delicate vanity mirror, walk in the lush grounds she played in as a child, see her water-encased grave in the middle of Althorp lake and lay flowers at a summerhouse nearby.

But there is a method behind the Diana "madness", as far as brother Earl Spencer is concerned, and that is to continue the charity work that she felt so passionate about. Charles Spencer decided to open the exhibition when she died, not as a bid to cash in, as he has been so often accused, but as a way of giving her in death what she loved to do in life.

Having opened three new rooms this summer season, it is a testimony to the fact that her lasting popularity can help others. The Princess Diana Memorial Fund brings in no personal profits whatsoever for the Earl, and one of the rooms is given over to displaying exactly how much has been achieved with the money.

Over £40m has been given in grants to over 250 organisations in the UK and worldwide and projects as diverse as working with asylum seekers to those suffering from AIDS in Africa, have benefitted.

Rushing in to meet the press, Charles Spencer looks like he hasn't aged a bit since he made his impassioned speech at her funeral in Westminster Abbey, but is nowhere near as sombre today.

Dressed in worn-in jeans with shirt sleeves rolled up, he looks as if he could have been gardening or tending to the flock of sheep he keeps at Althorp. But his casual appearance is tempered by a formal manner that marks the awkward relationship he has with the press.

He answers questions about his sister, about his nephews, about accusations of "cashing in" on Diana graciously but looks guarded throughout, standing up through the talk as if he were a passing visitor, almost as if he has one foot in the door, ready to run.

"I'm glad to see the accusations of 'cashing-in' are getting less and less every year as they are patently not true," he says.

"As far as the exhibition goes, it's turned out exactly what I would have hoped for. I have been asked to contribute to BBC obituaries for Diana and I have never contributed but I think the exhibition is appropriate. And I believe if she could see it, she would approve too."

He continues to talk about the overwhelming response the country displayed at the news of his sister's death and the surreal week which followed the fatal car crash. "She was probably the last person we expected to die, so it was unprecedented," he says. "I was amazed by the honesty of that week that followed her death in terms of people's responses."

He talks briefly about how Prince William and Harry have grown up, becoming the people she would have wanted them to, but is spiky when asked for too much detail.

"It's a difficult area to talk about because it's my role to be an uncle and a confidante and I'm not going to trumpet what I talk to them about."

It's not really until you meet Earl Spencer and you hear him speak about his beloved sister that the exhibition is taken out of the bounds of voyeurism and given some emotional depth.

The toys she played with have been put there lovingly, the home video where the young Earl's being hugged by little Di suddenly becomes poignant.

"At the end of the day, you have to remember I'm a brother who has lost a sister and I could never profit from her death," he says.

And it makes perfect sense when he says it. Except that his sister was not only loved by him but by the world, and what's so wrong with sharing a publicly-adored figure with the adoring public?