Anyone who had ever watched her address the nation was aware the Queen knew how to work the camera.

But there was one occasion when her ability to deliver a line on screen that would capture and enthral the audience took even the professionals by surprise.

Her Majesty had agreed to play herself having afternoon tea with Paddington Bear in Buckingham Palace on the occasion of her Platinum Jubilee celebrations.

The task was not an easy one, as she would be required to address a blank space in front of her – the computer generated image of Paddington was only later projected on to the screen through post-production wizardry.

But such was her ease and ability, she delivered her lines with an authenticity that might have fooled anyone into thinking she was a professional actor, rather than Britain’s longest serving monarch.

“She did it brilliantly and with evident enjoyment,” said the man who helped write the script for the afternoon tea skit, Frank Cottrell-Boyce.

The screenwriter and novelist said the Queen’s task was not an easy one. “Paddington’s not really there,” he explained. “So it’s technically an amazing performance.”

Dame Judi Dench, who has played her share of monarchs, including Queen Victoria and Queen Elizabeth I, agreed.

‘Her timing was perfect, completely on the money’

“Wasn’t she good? I mean really, really good,” she told Craig Brown in his forthcoming biography of Queen Elizabeth II: A Voyage Around the Queen.

Dame Judi adds: “Her timing was perfect. Every look, every line was just right. It was completely on the money – none of it overstated. Just wonderful.”

Of course this wasn’t the first time the Queen had played up to the cameras as a fictionalised version of herself.

A decade earlier, Her Majesty had taken everyone by surprise in agreeing to appear in a short film of her greeting James Bond at the Palace in order to assign him a very special mission, the opening ceremony of the London 2012 Olympics.

Visiting Buckingham Palace, Danny Boyle, the ceremony’s director, had been expecting to talk to her dresser for advice on what a lookalike Queen might wear to meet James Bond.

To his surprise Angela Kelly said she thought the Queen might actually be prepared to play herself.

‘She was very amused’

When Ms Kelly sent word upstairs the Queen not only agreed, but also chose the short film’s killer line.

“She was very amused by the idea and agreed immediately,” said Ms Kelly. “I asked if she would like a speaking part. Without hesitation, Her Majesty replied, ‘Of course I must say something. After all, he is coming to rescue me’.

“I asked whether she would like to say ‘Good evening, James’ or ‘Good evening, Mr Bond,’ and she chose the latter, knowing the Bond films.”

‘Good evening, Mr Bond’

Kelly adds: “I think he [Boyle] almost fell off his chair when I said that the Queen’s only stipulation was that she should deliver the iconic line, ‘Good evening, Mr Bond’.”

It seems the Queen had also anticipated the daring coup de theatre with which Boyle was planning to end the film.

When Edward Young, the Queen’s deputy Private Secretary began explaining the idea to Her Majesty she interrupted him to state: “I know – and then I jump out of the helicopter.”

And indeed, who could forget the sequence showing Queen Elizabeth jumping from a helicopter above the Olympic Stadium, before opening her parachute to reveal a giant Union Flag – only to then appear in the flesh inside the stadium, alongside thousands of cheering spectators and Olympic VIPs.

Jump forward a decade to Elizabeth II: The Sequel, when, in the final year of her long life, she played herself once again, this time with that bear from darkest Peru.

For Mr Cottrell-Boyce the sequence had particular resonance. “Paddington is an evacuee, a refugee, a one-time prisoner. Here he is being welcomed with tea and good manners,” he says.

“The most emotional moment in that encounter with Paddington is when the bear says ‘Thank you, Ma’am. For everything’.”

‘Archaic role’

Paying tribute to her unique role Mr Cottrell-Boyce adds: “I’m thankful for the way she used the peculiar power of her archaic role to allow us to glimpse, however fleetingly, that we share something good and we need to defend that.”

Not that Her Majesty succumbed completely to the louche backstage informality of the acting world. Far from it.

When the scene with Paddington was in the can, Simon Farnaby, the actor who played her footman, congratulated her on her performance, to which she replied: ‘Well of course, I do it all the time’.”

‘They’re actors. But I am the Queen’

Farnaby then overstepped the mark, prompting a glacial response.

“I said, ‘Ooh, you mean like playing the part of the Queen? And she said, ‘I beg your pardon? . . You know I am the Queen. Paddington’s not real, they’re actors. But I am the Queen’.”