Charles' letter written days after separating from Diana to be auctioned

A candid letter written by the Prince of Wales following his separation from Princess Diana is to be auctioned.

The handwritten note, on Royal Yacht Britannia crested paper, reveals his hopes of people appreciating "the things I try to do after I am dead".

Charles writes that it has been "pretty awful having to live through all the misinterpretation and the flak" following the break-up.

He adds: "Perhaps it is part of the test I have to go through in order to come out the other side having been tempered in the fire."

The letter, to interior designer Dudley Poplak, is dated December 11 1992 - two days after the couple's separation was formally announced.

It will be sold by Dominic Winter Auctioneers in South Cerney, near Cirencester, Gloucestershire, on June 14, along with a note from Princess Diana.

Auctioneer and senior valuer Chris Albury said: "We've seen a good number of letters from Princess Diana over the years and in among the short thank you notes are letters that have added poignancy and give insights into her personal life and character.

"Emotionally charged letters like this, which reveal her genuine interest in new age philosophy against a backdrop of a failing marriage are very collectable.

"Even more unusual is to have a very personal and revealing letter from Prince Charles to the same friend candidly expressing his pain and frustrations too."

Charles ends the letter to Mr Poplak, who died in 2005, by writing: "At least you understand, which is hugely reassuring and comforting.

"This comes with warm gratitude and countless good wishes."

The auction also includes a letter from Charles defending an attack on modern architecture in the BBC's A Vision Of Britain.

"I was trying to strike a blow for the 'ordinary bloke's' point of view and hope it will have encouraged some people to pluck up courage to call the experts' bluff!'," he wrote.

"Whatever I do I am only too aware that it is easy to accuse me of missing points out or of only voicing the lowest common denominator of taste!

"Perhaps in 30 or 40 years time I will be viewed as someone who got it all wrong and my memory will be reviled."

Mr Albury said the prince's views on modern architecture had remained controversial.

"It is 30 years since he wrote this letter and his views continue to draw praise and outrage in equal measure," he said.

A note from Diana, sent to Mr Poplak in February 1992, will also be sold.

She writes: "I have been fascinated by the contents of the Daily Meditations, as for a couple of years now I've followed the French philosopher Omraam Mikhael Aivanhov's way of thinking, but in my travels had not come across this particular edition."

White shoes worn by the princess when she was about aged 16 are also up for auction.

Mr Albury described them as "smart and practical designer shoes from a pre-princess time of youthful innocence".

In total, six lots - each expected to fetch between £200 and £800 - will be auctioned during the sale.