A heartfelt letter from Princess Diana to her psychic telling her 'how deeply I value our conversations' has emerged 30 years later.

Diana struck up a close bond with Rita Rogers, who she visited regularly for readings after being introduced by a mutual friend in 1994.

She even took her boyfriend Dodi Al-Fayed along to meet the medium, weeks before they both died in a car crash in Paris, on August 31, 1997.

Rogers, who was also close to Sarah Ferguson, the former Duchess of York, later claimed she told Diana shortly before she started dating Al-Fayed that she would become romantically involved with a foreign man with a name starting 'D'.

This prompted Al-Fayed to want to meet Rita and the encounter took place at her home in Lower Pilsley, Derbyshire, on August 12, 1997.

In the handwritten letter 'from the heart', Diana thanks Rogers for being 'immensely kind and generous to me' and adds that her friendship is 'enormously appreciated and treasured'. 

A month after Diana wrote the letter, her infamous BBC Panorama interview with disgraced journalist Martin Bashir was broadcast.

The correspondence, dated October 23, 1995 and penned on Kensington Palace headed paper, reads: 'This letter is long over-due, but comes very much from the heart.

'I did so want you to know how deeply I value our conversations and after all you give to others you still make time for this particular Cancerian!

'You, Rita, are immensely kind and generous to me and it is enormously appreciated and treasured - thank you.'

Diana flew with Dodi in a Harrods helicopter to meet Rogers at her home in Chesterfield, Derbyshire, on August 12, 1997.

The couple spent 90 minutes with the psychic. 

Diana is said to have consulted Rogers before giving her explosive Panorama interview, which Bashir obtained under false pretences, including by forging bank statements to convince the royal she had been betrayed. 

Rogers, who is of Romany origin and is now in her 80s, later recalled: 'She (Diana) rang at least once a week to see how I was, as well as for readings.

'When she came to visit, she used to throw her arms around me.

'She always used to leave me a present... we had such laughs and such a fantastic relationship. 

'I'd told her she would meet a man of foreign descent with the initial 'D' on water - and that the man would be connected with the film industry.

'Not long after, she rang me one day and said, 'Rita, guess where I am? I'm on a boat with a man I've just met called Dodi Fayed'.'

The two-page letter, which is signed off 'love Diana', has emerged for sale from a private collection at London-based Chiswick Auctions with a £1,500 to £2,000 estimate.

Specialist Valentina Borghi said: 'The current vendor acquired the letter on the London market a few years ago.

'We know that Diana relied on astrologists and spiritualists, hoping to find some emotional support and guidance.

'The general perception is that originated from the troubles in her marriage to Prince Charles.'

Diana died aged 36 on August 31, 1997.

The sale takes place on January 31.