Settling into an open carriage for a birthday drive through Windsor, the Queen had an unexpected surprise. On the seat lay a bouquet of flowers and, beside it, a card in an envelope.

First she smelled the flowers; then she opened the envelope and looked at the card, before bursting into laughter.

The card, which was signed by staff in the Royal Mews at Buckingham Palace, where the carriages and horses are kept, pictured the Muppet character Miss Piggy.

‘I thought: “Well, she can’t sack us all,” ’ said palace coachman Alfred Oates, who worked for the Queen for 57 years. ‘But there she was, as the crowds could see, laughing the whole way round.’

Queen Elizabeth II arrives for the 2007 Royal Variety Performance at the Empire Theatre in Liverpool

Some of the palace’s stuffier courtiers thought Oates and his team presumptuous, to say the least.

The Queen, however, was in on the joke. Years earlier, watching a video of herself, she had called out to her husband: ‘Oh Philip, do look! I’ve got my Miss Piggy face on.’

As Gyles Brandreth’s sparkling new biography of the late Queen reveals, this instinctive and self‑deprecating wit was as important a part of her personality as the clothes she wore and the smile that lit up her face.

And perhaps nothing was more central to that than her ability not just to make a joke, but to take a joke, too.

Time and again, she demonstrated that she could find the funny side in anything, however difficult the circumstances.

Take, for example, the infamous 1982 break-in at Buckingham Palace, when intruder Michael Fagan scaled a drainpipe and made his way to the Queen’s bedroom, where she lay in bed.

While the world was convulsed by the peril in which the monarch had been put, the Queen herself was preoccupied with perfecting the reaction of her chambermaid, Lizzie, when she saw Fagan.

For weeks afterwards, the Queen regaled her friends and family by imitating Lizzie’s broad Yorkshire accent. ‘Bloody hell, ma’am,’ she would say. ‘What’s ’ee doing ’ere…?’

Written by author and broadcaster Gyles Brandreth, Elizabeth: An Intimate Portrait – which is currently being serialised in the Daily Mail and Mail on Sunday – is littered with fascinating vignettes about our longest-serving but still enigmatic sovereign

She’d long known that humour was a priceless regal skill, not only during her public duties to put the overwhelmed and the lost for words at ease, but also in private.

On one occasion, exasperated by the behaviour of Prince Andrew, she sighed to her then daughter-in-law, Sarah Ferguson: ‘I am so glad you have taken Andrew off our hands, but why on earth did you do it?’ The laughter that followed the remark hid the shadow that was already stealing across the marriage.

The psychology of such comments is illuminating, of course. What then should we make of her observation to Andrew — as reported by Brandreth — after he had explained the sorry saga of his long relationship with the sex offender Jeffrey Epstein, and which led to him being stripped of his public roles?

‘Intriguing,’ was her one-word reply. Certainly, it illustrates her mastery of the understatement and also her liking for brevity. The Queen never ever said more than was absolutely necessary.

Dry and sardonic, yes, but also mysterious. It is tempting to wonder what Andrew made of it. Did he, as some have suggested, view his mother’s comment as a sign she had forgiven him, or was he as perplexed as the rest of us?

For years, the Queen’s ability to say nothing, while speaking volumes, was undoubtedly one of her greatest strengths.

When a government minister’s mobile phone rang — in contravention of the rules — as she took a meeting of the Privy Council, she cuttingly opined: ‘I hope that wasn’t someone important.’

With the Queen, duty always went hand-in-hand with laughter. Many of her friends have testified to how often she found things amusing and how, at times, they saw her laugh ‘till she cries’.

‘She had a marvellous sense of the ridiculous,’ one companion explained. ‘You only have to think of what happened the time she lost her lipstick in the loo.

‘It was at a private function and she’d gone off to the ladies’ accompanied by a lady-in-waiting. The lipstick rolled under the door of a cubicle, which was occupied — so they had to wait until the other person had gone before they could retrieve it.

‘The Queen thought the whole thing was extremely funny and couldn’t stop laughing about it.’

She would find humour in the most unexpected of places. Sir Michael Oswald, who was the Queen’s racing advisor, liked to tell the story of a horse she had in training called Harvest Song.

He made a call to her page, Barry Mitford, at Buckingham Palace one morning to say it was running in the 2.30 at Fontwell and that it was on TV, in case they wanted to watch it or record it for her. ‘Barry got rather excited at this, asking will it win and should he have a flutter,’ Sir Michael recalled. ‘I told him under no circumstances should he waste any money on it: that I had more chance of winning the 100m at the Olympics.’

Harvest Song started as a 50-1 rank outsider and won the race by five-and-a-half lengths.

When Sir Michael later rang the Queen to ask if she’d watched the race, she replied: ‘Oh yes, and may I say that Barry is standing next to me. If I was you, I would find some dark glasses and a good disguise next time you come anywhere near this place.’

So where did this sense of humour come from and how important was it to the Queen?

Some of it was undoubtedly inherited. The Queen Mother could be mischievous. ‘Have you been reigning today, Lilibet?’ she would ask her daughter in mock seriousness, as the Queen returned from an engagement.

Her quip when, aged 95, she learned that a masked intruder wielding a crossbow — intercepted in the grounds of Windsor Castle — had announced he had come to kill the Queen, could have come from her waggish mother. ‘Well, that would have put a dampener on Christmas, wouldn’t it?’

Queen Elizabeth II attends the Out-Sourcing Inc. Royal Windsor Cup polo match and a carriage driving display by the British Driving Society at Guards Polo Club, Smith’s Lawn on July 11, 2021

But at the same time, the Queen’s exposure to the male-dominated royal world where waspish asides and ruthless put-downs are part of the currency of palace life has also been pivotal.

‘It’s quick, sardonic and it’s observed,’ says one palace figure. ‘And the Queen loved it.’

Irreverent impressions were her forte. Aides recall the time a North Country mayor was introduced to the Queen and insisted on complimenting her by saying how much prettier she was in the flesh than in her pictures.

‘Later that day, the Queen did an impression of the poor man telling her this in a Northern accent, which had everyone holding their sides, including Prince Philip,’ says the retired courtier.

‘She wasn’t mocking him, just having fun.’

Michael Noakes, the distinguished artist, was at Buckingham Palace painting her for the City of Manchester in her Order of the Bath robes, and for the best light effect he had her standing near a window in the Yellow Drawing Room.

As he later told me: ‘She was peering out of the window and keeping up a running commentary of people’s reactions to seeing her standing there — “Gee, Maud [in an American accent] it can’t be” . . . “Oh no, he’s decided it can’t be, he’s moved on now.” And: “Ooh, a car has just been hit by a taxi, I think there’s going to be a fight.” She was very funny.’

Sir Antony Jay, co-author of Yes Minister and who also wrote the script of the ground-breaking 1969 TV documentary Royal Family, recalls finding the Queen to be not as he expected when he sat next to her at a lunch. ‘She’d just had her portrait painted and was rather acid about the artist rather than the portrait,’ he says. ‘She was confident and opinionated in a way you’d never see in public.’

Head coachman Colin Henderson recalls being with the Queen at the Windsor Horse Show when one of her grandchildren came up to her in the Royal Box. ‘The Queen said: “Did you have a good lunch?” and the child replied: “Yes, granny.” To which the Queen said: “I thought so — you’ve got it all down your front.” ’

One running joke involved Audrey Dellow, the organist for 40 years in the Royal Chapel at Windsor, who, according to Canon John Ovenden, competed with Her Majesty every Sunday over who was wearing the best hat.

‘She could see the Queen in her mirror because the organ was almost opposite the royal pew,’ recalled Canon Ovenden. ‘Everyone was in on the joke.’

Hats also featured when the Queen paid a visit to Washington in 1991.

For the official welcome, she’d been obscured by the height of a lectern, meaning only her eyes and hat were visible to spectators. So the following day, she began her address to a joint session of Congress with the words: ‘I hope you can all see me …’

Even in her final years, that impish humour remained firmly in place. Her appearance at last year’s G7 summit in Cornwall, eight weeks after Prince Philip’s funeral, was remarkable. It was not just the warmth she radiated among some of the most bombastic personalities on the planet, but her sense of fun. As the leaders of the world’s top economies jostled for the official photographs, she asked: ‘Are you supposed to be enjoying yourselves?’ with a knowing grin.

The subtext was clear: even if they weren’t, she certainly was. And her observation went a long way to show that she had emerged from her period of mourning and was returning to the fray to participate fully in the affairs of the kingdom.