Viewers have been given a rare glimpse into Christmas at Windsor in a new documentary starring the Queen.
The monarch, 91, revealed her boisterous great-grandchildren knock ornaments off the branches as she admired the giant fir tree installed at the castle.
In the touching festive scene, she and the Duke of Edinburgh are seen laughing and joking as they hand presents to their most trusted members of staff before heading to Sandringham for their annual Christmas break.
The footage appears in new ITV documentary called The Queen's Green Planet, which follows the monarch's legacy project to create a global network of protected forests across the Commonwealth - and her "sassy" manner has delighted viewers.
In the festive scene, the Queen can be heard chatting to the member of staff Neil Turner, who was tasked with putting up the tree.
She said: "The children love knocking those [baubles] off. Well my great-grandchildren do, anyway, they enjoy themselves.
"And the great thing is to make them decorate it... and then they're a bit more careful."
The stunning tree took between eight and nine years to grow and the Queen said it was one of the biggest they'd ever had at Windsor.
While handing out framed photographs to staff, the couple shared a joke with Michael Field, who is head of displays and framing pictures.
"I'd like to give you this. It's only a frame!" the Queen says drily, making the crowd around her laugh.
The documentary, hosted by David Attenborough, focuses on the vast network of native forests across Britain and the Commonwealth which is set to be protected forever in the Queen's name - and her love of gardening.
In one scene filmed last June, the Queen gives Attenborough a tour of the grounds of Buckingham Palace while pointing out her favourite trees and flowers that had been planted there over the decades.
But it was her cheeky sense of humour that had viewers gripped to their screens, with many calling her "sassy" and "so funny".
In one scene, the monarch playfully scolds Attenborough as he confuses the trees she had planted to mark the births of Prince Edward and Prince Andrew.
In another, she pointed out a lopsided sapling, joking that they "won't put that in" the film.
And clearly delighted by her deadpan humour, one viewer tweeted: "The queen is a sassy little thing isn't she.(?)"
Another viewer wrote: "Drinking tea and watching the Queen being sassy to David Attenborough feels like the most British way I could possibly be spending a Monday evening."
Their sentiments were echoed by actress Angelina Jolie, who described the Queen as a "lovely lady" as she spoke about the QCC project towards the end of the documentary.
As the programme concludes, Sir David discusses the importance of her legacy with the monarch.
"The trees with which you will be presented are going to change as our climate changes and there will be all kinds of different trees growing here in another 50 years maybe," he says.
"It might easily be, yes," she says, before pausing for comic effect and adding: "I won't be here though."
Speaking to the Radio Times about the interview last week, Sir David confessed to being nervous before the meeting - but said the Queen was "very gracious".
He said: "There was a certain amount of apprehension because all sorts of things could have gone wrong.
"There were problems in that where the palace is, geographically, there are always police sirens and ambulance sirens that make filming difficult. But she took it all in her stride.
"It was a privilege of course, a very nice occasion - and she was very gracious."