For six hours all she could do was gaze through the glass at a landscape she had, for 72 years, shared with her mama, and simply remember.
With nowhere to turn inside her royal Bentley except to the circling cinema reel of her own thoughts, the Princess Royal followed the late Queen’s coffin as it made its slow progress from Balmoral to Edinburgh on Sunday.
With all eyes trained on the hearse and the grief of the well-wishers who lined the route, it was easy to forget the small figure who travelled and grieved behind; easy, indeed, not to realise she was there at all.
Yet all the time, Princess Anne, alongside her husband Sir Timothy Laurence, was absolutely there, dutifully and resolutely, as she was by her mother’s deathbed on Thursday.
The first to sound the family alarm - as she was yesterday marching with her siblings behind the hearse, and as she will be today (Tuesday), accompanying her mother’s coffin on its flight from Edinburgh to RAF Northolt.
Those six hours on Sunday would have surely been the longest, most confronting and painful of her life?
You imagine her silently replaying every trip she had ever made through these treasured hills, glens, farms and fields with her mother by her side.
Every visit they made together to those villages and towns.
Yet when we caught a glimpse of her pale face, framed by its familiar chignon, the stiff "cottage loaf" hairstyle that rarely alters, it remained composed.
Taut with grief and emotion, but set.
The stoicism is typical of Queen Elizabeth II’s only daughter, who admitted once she was not “everyone’s idea of a fairytale princess”, yet has earned a reputation as the hardest working royal - carrying out over 20,000 engagements, characteristically without fanfare or fuss.
When she arrived at the Palace of Holyrood House after her arduous journey, she was still able to find the strength to give one final curtsey, the only clue to her pain, Sophie Wessex’s fleeting, knowing, arm of comfort on her back.
It speaks volumes that it is believed the former Queen herself selected Princess Anne to be her companion for this final journey.
It was her daughter’s commitment and poise, no more evident than now, that had made her her mother’s right hand woman in later life, and enriched an ever closer bond which saw them speak nearly every day.
Royal biographer Penny Junor said: “She has never been the show pony, she is not there to promote herself.
"What she demonstrates is the monarchy is not about glamour or being a glitzy celebrity.
"She is like her mother in that she has dedicated herself to her role.”
While her brothers have tended to steal the limelight, Princess Anne has diligently forged her own role and worked tirelessly.
Like King Charles, she is known to skip lunch, surviving often on little more than a kiwi fruit - her handbag staple of choice.
Apparently it was not at her bidding Sunday’s cortege stopped for a brief break after three hours.
Yet often her efforts have gone largely unnoticed.
She was famously her father’s favourite.
As a headstrong girl with his inability to suffer fools and sporting prowess - she was the first Royal to compete in the Olympics in 1976, in equestrian events - she and Prince Philip were two peas in a pod.
In her younger years Anne had a rebellious phase. She demonstrated a temper, once telling photographers to “naff off “.
She was dubbed Her Royal Rudeness.
Reportedly, there were flings, even a tabloid kiss and tell from her once police bodyguard.
Netflix ’s drama The Crown made infamous the supposed relationship she had with the now Queen Consort’s first husband, Andrew Parker-Bowles.
Princess Anne has been married twice herself, divorcing from her first husband Mark Phillips in 1992, and marrying her second husband just eight months later.
But in more recent years, it became clear the late Queen came to depend upon her.
During the pandemic, it was to Princess Anne she turned for help with her first Zoom meeting.
Their chumminess was obvious when they joked there should be six faces on the screen, but Her Majesty could only see four.
Ah well, chuckled the Princess Royal, “you don’t need me, you know what I look like”.
They shared a love of animals, particularly horses, horse riding and racing.
In a previously unseen interview with ITV broadcast on Sunday, Princess Anne explained for she and her mother, when you live a “rather restricted life”, horses become more important because they “give you an opportunity to take you right out of that zone”.
Her mother is said to have admired her choice not to grant her children, Peter Phillips and Zara Tindall, royal titles.
The modest way in which she relentlessly carried out her duties was closer to Elizabeth II’s own model.
Princess Anne has said she followed her mother’s example. “It was about listening, and it was about learning,” she explained.
During the Diana years, when her sister-in-law drew the lenses, Princess Anne, a self-proclaimed “fuddy duddy” who has recycled her clothes for decades, shunned them.
Penny Junor recalled once accompanying her on a royal tour to Uzbekistan in July 1993 – clashing with Princess Diana’s trip to Africa.
While Diana hugged children, Anne stood back from those she met. The papers barely covered her trip.
Junor said: “Her explanation would be, ‘What child wants a complete stranger to hug them?’
“And, ‘I’m much more useful finding out from the doctor what problems she faces before I go and meet the President and voice those concerns’.
“She does not want the glory for herself and she does not want to be on the front pages.”
It is fitting then - and the late Queen would have known it - that Princess Anne remained her closest companion until the end, leaving King Charles III to garner the headlines.
She knew her daughter could take her weight. She knew it would be her daughter who could best withstand this final journey by her side.
