A window at Harrods leaves little doubt about the nature of the relationship between Princess Diana and Dodi Fayed.

Separated only by a cascade of white lilies and ivy, their twin portraits stare out above the dates of birth and death, as if to say, if ever there was a pair of star-crossed lovers ...

According to Cindy Crawford, supermodel and friend of Diana, the couple had been going out since last November and not, as had previously been reported, only this summer, and that it was the "real thing".

"With Dodi, Diana was truly happy. She understood that she had found in him the companion she had been searching for in her life," said Craw-ford, who went on a secret late-night shopping trip to Harrods with Diana last Christmas. But if Dodi was truly Diana's "soul mate", as many of the mourners who have been leaving floral tributes to them this week clearly believe, she was a long time in recognising it.

She and Dodi first met 11 years ago at the Guards Club in Windsor when Mohamed Al Fayed revived the Guards' polo tournament in which both the Prince of Wales and Dodi played. At the time Diana was a married woman and the relationship did not flower. However, Mr Fayed's wife, Heine, was close to Diana's father, Earl Spencer, and he was soon being treated to lavish hospitality at Harrods. In 1990, when Mr Fayed launched a book on the history of the Knightsbridge shop, Earl Spencer insisted on making the main speech. Mr Fayed became a regular visitor to the Spencers' country home and it wasn't long before Diana's stepmother, Raine, was installed as a director on the board of Harrods International.

Although Diana continued to run into Dodi on and off at official functions, the impetus for the development of their relationship appears to have come from Mohamed's decision to invite Diana and her two sons to holiday on his yacht off St Tropez in the summer. At the end of it, Diana supposedly confided that it was "the happiest of her life". In a comment that was to cause endless speculation, she also told the paparazzi that she had a "surprise" announcement in store.

What she meant by this we shall never know. But with the revelation this week that Dodi had presented her with a diamond ring during their final dinner at the Ritz Hotel in Paris on Saturday, it is at least possible that she was indicating she had sensed Dodi's intentions, and possibly her own.

During her last holiday with Dodi in Sardinia, Diana called Crawford and told her: "For the first time in my life I can say that I'm truly happy. Dodi is a fantastic man. He covers me with attention and care. I feel newly-loved."

Dodi also left friends in no doubt about his feelings. "She fills up my senses," he is reported to have told Max Clifford, quoting a song by John Denver. It is also claimed that four hours before the crash he told a relative staying at the Ritz that he and Diana had "decided to get married".

In Dodi's Paris apartment relatives found a gold cigar clipper inscribed "with love from Diana". The Princess had also given Dodi a pair of cuff- links that used to belong to her father. In addition, Dodi had inscribed a poem for Diana on a silver plaque and placed it under the pillow at his apartment.

"It is quite clear that the relationship was a sincere one on both sides," said Michael Cole, spokesman for Dodi's father. How sincere will now never be known.