Any other year, she would have been busy in her first-floor study putting the finishing touches to arrangements for her former husband's birthday party.
Any other year the woman who clung like a limpet to her royal status decades after divorcing the King's younger brother would have noted with satisfaction the names on the guest list: old friends of Prince Andrew still loyally standing by him and the new acquaintances the pair were eager to do business with.
It has always been this way with a celebration to mark the February 19 anniversary of the birth of the late Queen Elizabeth's younger and, it is said, favourite son – part fun, part schmooze-fest.
At his 60th, friends wryly noted the presence of Chinese nabobs among the 60 guests who sat at ten circular tables lapping up the royal largesse.
But this year, on his 66th birthday, there is no party and in a couple of weeks, when chauffeur-driven limousines should have been depositing the monied and the glamorous at the doors of palatial Royal Lodge, deep in Windsor Great Park, there will be silence.
Indeed, if she were still in residence, Sarah Ferguson could have listened to the solitary echoes of her own footsteps in the vast saloon with its floor to ceiling picture windows.
There in past years butlers, drafted in from nearby Windsor Castle, were greeting the guests with champagne while braying laughter would meet Andrew's attempts at humour – on his 50th he amusingly described himself as a man 'with three children'.
He didn't need to spell it out to the 120 present on that occasion that, in addition to Beatrice and Eugenie, he was including their mother, his permanent house guest, too. For now, and for the foreseeable future, the impossibly grand good life is over not just for the ex-duke but also for the ex-duchess.
As Andrew Mountbatten-Windsor left Royal Lodge for the last time earlier this week under cover of darkness – along with a convoy of removal lorries – bound for his brother's Norfolk estate at Sandringham, the wife from whom he was never parted despite divorcing 30 years ago, was slipping quietly away and heading in the opposite direction.
Her ultimate destination is not known. According to friends she will be 'overseas' for several weeks.
Some suspect she will be based at her daughter Princess Eugenie's home in Portugal. Others suggest she may be travelling further afield to Australia, where her sister Jane Makim has long lived.
Once her bulging address book would ensure she could be folded into discreet social currents almost anywhere on the planet she wished.
How striking then that some of her old circle were insisting she was not with them, among them the Virgin tycoon Sir Richard Branson who said she was not on his private Caribbean island, while another friend holidaying on exclusive Mustique, the royals' favourite hideaway, tells me she's not there either.
All we can be sure of is that she won't disappear for long. And then? 'Well, she won't be hiding away,' says a close figure.
'It is not her style. It's true she needs some space now; this whole saga has dominated her life for the last five years, making it impossible for her to think about anything else.
'She has been in the middle of it all and it has undermined her resilience.'
Being away from Royal Lodge, away from Andrew, will, says her friend, enable her 'to be reputationally freer.'
According to this same figure, however, she will continue to live in Britain.
The details are still to be finalised, but I am told she has found a property in Windsor which she has identified as the place where she can 'rebuild her life' and 'start again.'
A comeback? Really?
As someone who has reported on Fergie from the moment she first entranced the then Prince Andrew by feeding him chocolate profiteroles at a Royal Ascot house party, I've witnessed all her reinventions.
For years she was the royal family's retread queen, swerving from one catastrophe to another and still somehow surviving and, yes, thriving.
Twice she swerved bankruptcy and bounced back. Even the abject humiliation of those notorious toe-sucking photographs and her alleged affairs didn't really dent that impregnable self-confidence. Instead she monetised her (and the Royal Family's) embarrassment by writing a book and making a film. Life lessons became a business opportunity or nice little earners.
Fuelled by a lack of self-doubt, she has always thought she could outsmart any situation and when things did go wrong, convince herself it was either someone else's fault or a freak of circumstance.
Even after she was unmasked attempting to sell access to Andrew through the notorious 'fake sheikh', she managed to retain her reputation with a forgiving public as an accident-prone but essentially harmless adornment to national life, admired for her ability to recover from adversity.
But however much shame and opprobrium she received, two things always insulated her – the Duchess of York title that she prized above all else and the luxury of Royal Lodge, the graceful imperial address where she could retreat to lick her wounds and where she was always treated as royalty. Now both have gone, along with her quasi-royal standing.
And as the trickle of correspondence between her and Jeffrey Epstein has become a flood, the only question is why it didn't happen sooner.
It is tempting to wonder how the King, having welcomed her back into the Windsor fold with an invitation to return behind the royals' velvet rope that Christmas Day at Sandringham just two years ago, must feel now. Even if he didn't know the full extent of her extraordinary egregious dealings with Epstein, she certainly did.
Charles is left with questions about his judgment when, really, Fergie should have resisted his kindness and any rapprochement.
For surely, she must have known that every word of her incomprehensibly misjudged dealings with the grotesque financier would eventually come spewing out at the tap of a computer key.
Surely too she must have known that it was not just her relationship with Epstein hiding in plain sight but the relationship she also exposed her daughters to.
He was, remember, a 'level three' sex offender, indicating minors to be at greatest risk, yet here she was just five days after his release from a Florida jail in July 2009 after serving 13 months for soliciting a child for prostitution, planning to drop by for lunch at his Palm Beach home accompanied by Beatrice and Eugenie, then aged 20 and19.
He was also under house arrest. No matter as Fergie writes: 'What address shall we come to. It will be myself, Beatrice and Eugenie. Are we having lunch?'
The answer appears to have been yes, as Epstein suggests a menu of 'vegetable lasagne, or anything else you would like, chef here from Paris.'
During the exchange Epstein asks whether 'Sarah' needs a lift, but the response is: 'No thank you I made Philip (thought to be former Miami mayor Philip Levine) give us his car and a back-up one for the policeman.' The dialogue ends with her asserting: 'Cannot wait to see you.'
It is not hard to imagine how the two princesses must have squirmed at seeing their names being dragged into this squalid saga as the trove of Epstein Files made public by the US justice department has been opened up over the past seven days.
At times, the email trail suggests that the two girls – granddaughters of the late Queen Elizabeth and with the style HRH, unlike their parents – were almost being used in a transactional manner. The emails themselves range from the demeaning to the shameful.
There is a request from Epstein to 'Sarah' that 'you [or] one of your daughters' show someone (whose name is redacted) around Buckingham Palace' as though these two princesses of the royal blood are little more than hired hands. And how does Ferguson respond? With acquiescence. 'Of course,' she replies.
In subsequent correspondence, Epstein asks Ferguson if there was 'any chance of your daughters saying hello' to one of his associates who was in London in July 2010. The person's name was not revealed. Fergie answered that Beatrice was in London with her father and that Eugenie was 'away with a cool boyfriend'.
Who knows if the meeting took place, but Fergie appeared to voice no objection to her daughters being reduced to meeters-and-greeters.
Referring to a separate occasion, she apparently writes to Epstein, apologising that 'the girls were not around this weekend', adding: 'Shows I don't crack the whip when I am not in the country!' The message continues: 'Actually, eugie was in france and beatrice was out with dave [thought to be Beatrice's then boyfriend, entrepreneur Dave Clark]'.
And then there is the March 2010 exchange from 'Sarah' to Epstein with its shockingly coarse remark that she is 'just waiting for Eugenie to come back from a shagging weekend!'.
While there is no suggestion of any wrongdoing by the princesses, what emerges is their unwitting role as stooges in their mother's (and father's) desperate and distasteful quest to suck up to the wealthy Epstein. 'Oiling the wheels,' as one palace insider put it. With their royal highnesses' titles, they brought added lustre.
Fergie especially comes across as a needy, desperate figure, chasing money and support, but one also prepared to play the victimhood card. In one instance she describes herself to Epstein as 'very traumatised and alone. I am wanting to work for you at organising your houses.'
She follows it up with a further plea the following month: 'When are you going to employ me', and the same day, 'phew… you still love me'.
As more emails emerge, there is a growing impression of how much she seemed to depend on Epstein, telling him he was her 'pillar' and confiding 'I have been so sad'.
These exchanges, of course, were after her greed had been unmasked by the fake sheikh episode and she was fearing the consequences of her foolishness.
Melodramatically, she declared to Epstein: 'No woman has ever left the Royal Family with her head… I am now 1,000 per cent being hung out to dry.'
Those of us who have followed Fergie's journey, from the ski slopes of Switzerland where she worked as a chalet girl, to duchess, divorce and trotting around the globe with lovers during her marriage, are familiar with the effusive, gushing language she uses in her email correspondence.
Courtiers still recall her flagrant misuse of her status – the ludicrous and costly helicopter flying course, abandoned when she became 'bored' with the lessons; those vast piles of luggage for official trips and the endless shopping expeditions.
She always sailed perilously close to the wind and there was always a chance that she would one day find herself in serious difficulties.
Despite all this in her second memoir, A Duchess's Journey To Find Herself, she railed about the nicknames she was given because of her profligacy. 'Freebie Fergie' particularly stung.
'I tried to save money where I could,' she wrote. 'I found that some designers would allow me a deep discount in return for the publicity value of my wearing their fashions… I was merely trying to be frugal! I should have been called 'Frugal Fergie'.'
That same Frugal Fergie spent herself into debts of £4 million in the 1990s and £5 million in 2009.
When it was pointed out that she had been given every advantage in life, including marriage to a prince, and that she only had herself to blame for throwing it away, she didn't like it. I became used to late-night calls when a sometimes overwrought duchess would sob down the telephone at something I had written that she found disobliging.
I was in the room when the full ghastly horror of the toe-sucking pictures was relayed to her at Balmoral by her American lover John Bryan.
On other occasions there would be invitations to a fashionable restaurant, where she would firmly give me the benefit of her point of view over a costly expense-account lunch. The private room at Mosimann's, the much-garlanded central London dining club, was a particular favourite.
Once, on an assignment in eastern Europe, there was an urgent summons to her hotel suite for what the Army call an 'interview without coffee' or 'dressing-down' – we clinked glasses of vodka, watched over by edgy assistants hovering in the background..
She often used to talk about Princess Diana. Where once they were whisper-close, they were estranged at the time of her death, a source of endless regret to Ferguson.
As she ponders her future stripped of her royal status and cut adrift by her charities, her latest book withdrawn from sale and pulped, there will be a lot more regrets crowding in.
For now, she is finally where Prince Philip always wanted her – out in the cold.
