London, Dec 14 (ANI): Princess Diana wrote affectionate letters to her father-in-law Prince Philip, the Duke of Edinburgh, referring to him as "Dearest Pa," the ongoing inquest into her death has heard.

Extracts from the letters, in which Diana thanked Prince Philip for his "heartfelt and honest" words and praised his marriage guidance skills, were shown to the jury on Dec 13, reports The Sun.

In one, she wrote: "Even if you are unable to succeed in this, I still would like you to know how much I admire you for the marvellous way in which you have tried to come to terms with this intensely difficult family problem."

In his reply, the Duke wrote: "If invited, I will always do my utmost to help you and Charles to the best of my ability, but I am quite ready to concede that I have no talents as a marriage counsellor!!!"

To this, Diana responded: "Dearest Pa, I was particularly touched by your most recent letter which proved to me, if I didn't already know it, that you really do care."

"You are very modest about your marriage guidance skills and I disagree with you.

"This latest letter of yours showed great understanding and tact and I hope to be able to draw on your advice in the months ahead," she added.

The letters were produced by the Duke's private secretary, Brigadier Sir Miles Hunt-Davis, though the intimate details were not disclosed.

Diana's lover, Dodi Al Fayed's father Mohamed Fayed believes the couple were assassinated by MI6 agents, arranged their car crash in Paris in 1997 on the orders of Prince Philip, and then masked evidence of a "pregnancy".

The inquest also heard from a detective leading the British investigation into the death of Diana.

Detective Superintendent Jeffrey Rees, who was appointed by the Metropolitan Police to head a UK-based inquiry into the crash, said that e "periodically" asked French police if they had found anything suspicious.

Rees was in touch with French investigators through Nick Gargan, then a police liaison officer based in the British Embassy in Paris.

Gargan, now Assistant Chief Constable of Thames Valley Police, told the inquest at London's High Court it was his role to act as an intermediary between UK and French detectives.

He was asked why Rees - a member of Scotland Yard's serious crime group - was put in charge of the British side of the inquiry.

"Everybody involved in this had a sense that it was a momentous investigation. It was a real moment in history, and I think everybody decided they were going to put their best people on it," Gargan replied. (ANI)