She said: ‘He invited me to Windsor for the weekend as we’re walking I’m seeing a table outside and there’s people sitting round it and I’m thinking that looks like the Queen and I remembered my dad had said to me that if you ever meet the Queen he said you curtsy and call her ma’am.

‘I grab her hand like this [handshake], forget all about the curtsy and I’m like really really pleased to meet you, really pleased to meet you.’

Shane then asked: ‘Did you know Diana much?’

Ruthie replied: ‘I met her a couple of times and one of my favourite times was we were at Balmoral, there was Diana, The Queen, Margaret, the Queen Mother, Charles, Edward, myself.’

She added that Diana was ‘lovely’, however she doesn’t ‘remember an awful lot because Charles gave me my first martini’.

‘I’d never tried it before so I was fairly… I had two of them and I was like woah…’, said Ruthie prompting Shane to tease: ‘Don’t tell me you go into show tunes.’

‘Let me tell you. Margaret she goes “yes, yes, oh sing us a song from that show you’re in” and I was in Les Mis at the time. So I sang I Dreamed A Dream and I must have changed key three times because I was so p****d on martinis.’

Ruthie also reflected on how she met Edward. She said: ‘It’s funny, it’s such a long time ago.. [he’s a] Lovely bloke. And I genuinely fell in love with him.

Shane then asked: ‘There was a headline years ago wasn’t there? The prince and the showgirl. Where did you meet him?’

She responded: ‘He was a production assistant at Andrew Lloyd Webber’s. And he then called me himself [Andrew] and he wanted me to play the lead in A Star Is Born. And Edward was my point of contact.

‘He was the one who’d call me up and say you’re rehearsing at 2 o’clock or whatever.

‘And he said to me would you like to come to mine and watch the film of A Star Is Born with me and you can have some dinner. I was like what, at the Palace, is that where you live?’

Ruthie dated Prince Edward on and off for five years and remains good friends with him, even attending his wedding to Sophie, Countess of Wessex.

However, Ruthie admitted she regretted making the comments in retrospect, saying: ‘I only said it to make Shane laugh. Then I quickly became aware everything is being recorded.’

Ruthie and Edward separated in 1993, as she chose to focus on her career and went on to star in hit musicals, including Chicago, Billy Elliot, Oliver! Miss Saigon and Cats,

She went on to marry Canadian singer Timothy Howard and have two daughters.