According to a new video released 20 years after Princess Diana’s notorious Panorama interview, the Queen once described it as “frightful.”

Shortly after the 1995 broadcast, Her Majesty expressed her thoughts over lunch with Sir Richard Eyre, former director of the National Theatre.

Diana conducted her interview on November 20, 1995, and mentioned Charles’ romance with Camilla Parker Bowles, who married Prince Charles in 2005 and is now the Duchess of Cornwall.

‘I had lunch with the Queen not long after and she said to me unprompted, ‘How are things at the BBC?’ and I said, ‘Oh well, fine’. And she said, ‘Frightful thing to do, frightful thing that my daughter-in-law did’,’ says Sir Richard, who was a BBC governor at the time.

His remarks are included in Diana: The Interview That Shocked The World, a new Channel 5 documentary.

It contains crucial figures from the original show’s development and transmission, which brought more than 20 million viewers to see Diana expose the secrets of her marriage.

“Well, there were three of us in this marriage, so it was a bit crowded,” Diana famously said when asked about her husband Prince Charles’ romance with Camilla Parker Bowles.

Sir Richard argues in the new documentary that Diana did her make-up specifically to appear distraught and obtain compassion from the public.

‘It’s like somebody who has been very, very tearful, and then run out of a room and come back ten minutes later having restored their make-up,’ he adds.

‘I think that’s a conscious decision. I think that she presented herself as a victim. The artfulness of the appearance of spontaneity – that’s acting.’

Diana stated at the time that, while she would never be Queen, she aspired to be “a queen in people’s hearts” if she divorced Charles.

“I’d like to be a queen of people’s hearts, in people’s hearts, but I don’t see myself being queen of this country,” Diana said.

“I don’t think many people would want me to be queen,” she said, and her remarks were well taken by the public, who praised the interview’s candor.

The Princess also opened up about her struggle with post-natal depression following the birth of William.

“I was unwell with post-natal depression, which no one ever discusses, post-natal depression, you have to read about it afterwards, and that in itself was a bit of a difficult time,” she explained.

“You’d wake up in the morning feeling you didn’t want to get out of bed, you felt misunderstood, and just very, very low in yourself. I had never had depression in my life.”

The Queen wrote to Charles and Diana individually, encouraging them to divorce, within a month of the show being broadcast.