EXCLUSIVE:The ‘awful’ moments after Diana’s death, polo with William and unseen pictures of the Prince and Kate: Designer who befriended the Princess tells all as she puts three of the royal’s dresses up for sale (and they could fetch up to £1million)

Stepping out of a chauffeur-driven Jaguar into the balmy warmth of a summer’s evening, Princess Diana smiled briefly for photographers as she walked into London’s Dorchester hotel for a charity fundraiser hosted by former cricketer Imran Khan and his wife Jemima.

It was Independence Day, 1996, and Diana betrayed no hint of what had happened just an hour earlier: at 6.30pm the then Prince Charles’ solicitors Farrer and Co had delivered an offer for a divorce settlement to the London officers of her advisers Mishcon de Reya.

Instead, the Princess, who described herself as ‘Queen of Hearts’ in her notorious BBC Panorama interview, was confidently looking to the future, as confirmed by one of the fundraiser’s most generous guests – American couturier and bridalwear designer Pat Kerr Tigrett.

In fact, Diana was planning what would become a famous charity auction of her evening gowns at Christie’s, in New York, along with a trip to Memphis, Tennessee, to visit the St Jude Children’s Research Hospital and take a tour of Elvis Presley’s Graceland Mansion.

Pat, who is on the board of the hospital, bought four of Diana’s dresses at the Christie’s auction and became a friend of the late princess.

‘I was talking to her about the hospital,’ she says. ‘She already knew about St Jude and was very involved in the charity, so I invited her to come to Memphis and see the hospital for herself.

‘Her eyes just lit up and she said: “I would love to do just that. I could bring the boys [Princes William and Harry] with me.”

Pat is now selling three of Diana’s dresses via Julien’s auction house in Los Angeles and they could raise up to £1million – not bad for an £80,000 investment