Anna Wintour’s announcement about stepping down as editor-in-chief of US Vogue after 37 years sparked a frenzy of reactions and speculations last week.

Is Anna leaving Vogue? Or is it Vogue leaving Anna? Is this finally the end of the power of fashion magazines? Who will take over from her?

As someone who has been through the process of leaving a long-held position as a Vogue editor, in my case as the editor-in-chief of British Vogue, I can relate to the whirlwind of emotions that come with such a significant change.

What is certain is that the manner in which any of us leaves that chair is as defining as all the work done prior to that moment.

There is a lingering question surrounding the timing of departure from Vogue. While Wintour informed her team recently, it is likely that she had informed the Conde Nast board well in advance.

In my case, I left Vogue three times – and each moment was highly emotional.

The first was when I resigned in the office of Nicholas Coleridge, president of Conde Nast International and my immediate boss. I had taken a dawn Eurostar from my suite at the Paris Ritz where I had been at Chanel’s Metier D’Arts show and made my way straight to his office on the top floor of London’s Vogue House.

The decision had been a secret I’d hugged closely for some time before I could bring myself to tell anyone. I had been in the job for 25 years and didn’t feel there was anything left for me to achieve. If I left now, I told myself, I’d be leaving on a high after Vogue’s high-profile centenary year.

When I told Nicholas I was leaving, I wobbled for a nano-second as he offered me more money to remain, but I was convinced my future lay outside Vogue. I stuck to the plan.

Still, it was a daunting prospect to willingly fling myself out of my cashmere-lined nest into unemployment. Not many journalistic jobs carry such an aura of glamour. But even before the role was immortalised by Meryl Streep in The Devil Wears Prada – which is based on the memoir of Wintour’s one-time assistant – the editor of Vogue was a newsworthy role.

Wintour’s predecessor Grace Mirabella learnt about her defenestration via the TV news. When I was appointed in 1992 to British Vogue, a fashion nobody, the New York Times ran a long piece on the appointment. All the British newspapers had been offering sweepstakes on who would get the job.

As Vogue editor you are an ambassador, a deal-maker, a taste‑maker, a news-breaker – or, at least, that used to be the job. In my day, feted by designers who wanted to feature in your magazine, you could order clothes direct from the runway, either free or with a large discount.

Excellent tables were available at restaurants such as Le Caprice, Cecconi’s and The Wolseley, while hard-to-come-by tickets for the theatre, ballet, opera and many sporting events could be magicked up.

I had a clothes allowance, unlimited executive cars, first-class travel and splendid hotel rooms.

Since I worked in London, not New York, I did not have the American perks, which were even more extraordinary – interest-free mortgages, an expense account which meant you could fly your nanny with you across the world, and not one, not two, but a battalion of personal assistants.

In Anna’s case, one would be deputed to take her dry cleaning home to her house and hang it in her wardrobe. Even so, giving up the luxuries I had was no small thing.

To clarify, although Anna Wintour has left her role as editor-in-chief of US Vogue, she remains chief content creator for Conde Nast and global editorial director for Vogue.

She still reigns supreme over the countless editions of that title across the world, plus all the international iterations of the other magazines published by Conde Nast such as GQ, House & Garden, Architectural Digest, Tatler and Vanity Fair. At the age of 75, hers is still an incredibly powerful job.

Indeed, Anna Wintour has never (as far as anyone can tell), ever, previously given up a sliver of her workload. ‘Bring it on’ seems to be her mantra.

Overseeing the cover choices of Vogue Netherlands, approving the appointment of an art director of GQ Thailand, chucking out a 12-page spread in US Architectural Digest and, while you’re at it, advising Lauren Sanchez Bezos on her wedding gown.

When Wintour wanted to celebrate her elevation to the highly prestigious cadre of Companions of Honour, a squadron of Vogue staff were involved in inviting the Beckhams, Roger Federer, James Corden, John Galliano and other family and friends to a dinner at London’s Spencer House, hosted by Dame Hannah Rothschild.

This is not the life that will be coming to the new head of editorial content at US Vogue, which it is now advertising for.

The brilliant characters who now oversee the international editions of Vogue for Wintour do not have the same wonderful job Anna had, or that I had.

They don’t have total independence over what they run in their magazines. They don’t run a fiefdom where their personal tastes, opinions and style are reflected in the publication they edit.

They don’t have entire discretion over who they hire, but instead oversee ‘content’ – that dismal word that encompasses a mass of words, pictures, videos, events and social media, while having to kowtow to the morass of decision-makers based in New York.

It’s a big job for sure, but I suspect not nearly as enjoyable as the one I had.

Which is probably why leaving the old-style editorship is so hard.

The second time I ‘left’ Vogue was about eight weeks after telling my boss – when I was finally allowed by the company to break the news. My staff had been alerted to a meeting in my office; the Press office was primed to press ‘send’ on the announcement as I spoke.

I looked at them all, around 50 people squished into the room, and remember feeling a deep sadness; but also, as I frequently did, supported by their presence, trying hard not to cry as I told them why I wanted to leave and how brilliant they had been.

It’s a strange limbo when you are still in the job but everyone is speculating who will follow.

For anyone who is superstitious, it is strange that the night before the official announcement, I dreamt that actor Idris Elba was to be the first black James Bond. At that stage I did not know my successor would be the Ghanaian fashion editor Edward Enninful.

But after the late Franca Sozzani, long-time editor of Italian Vogue, was replaced by a man, the rumours had grown that it might be Enninful who would replace me.

At lunch with my boss Jonathan Newhouse, chairman of the board of Conde Nast, he told me he wanted continuation not revolution, but he also mentioned Enninful, one of his best friends whom I knew would want a very different magazine.

When I said that would be another male Vogue editor, he told me: ‘I only care what’s between their ears, not between their legs.’

Fashion’s business titans were equally abrupt. On the phone to the retail businessman Philip Green after my announcement, I held the phone away from me as he bellowed: ‘You’d better get everyone you want to talk to on the phone now, since once you’ve gone they won’t take your calls.’

This is the stage Anna is now experiencing. Busy as she will be, she will be aware that there are those who have been hanging around waiting for this moment to bring out all their gripes and grievances.

There will be many who have experienced her curt manner. Though I generally got on well with her, she could be brutal when she wanted to be, especially if she wanted something for her magazine that conflicted with what I wanted for mine.

She could be mind-numbingly abrupt, veering into all-out rudeness. But I lived to tell the tale after she put the phone down mid-conversation a couple of times.

She can also be ruthless, as in the way she cut loose the photographers who had helped build her Vogue – Mario Testino, Bruce Weber and Patrick Demarchelier – at the first hint of scandals over inappropriate behaviour. She hasn’t stayed at the top without a well-honed survival instinct.

‘What Anna wants Anna gets,’ has been the status quo for years, and while she is loyal to her favourites, like all of us she is fallible.

Many of her suggestions concerning the direction of the magazines other than Vogue haven’t worked out. Years back her desire to turn the American edition of House & Garden into an interiors Vogue called HG was short-lived. It quickly reverted back to House & Garden then folded in 2007. It is still going strong in the UK.

Her habit of giving out editorships to those who have worked directly under her (some might call it loyalty) hasn’t always panned out – there is a big question mark over whether the recently appointed editor of Vanity Fair, Mark Guiducci, Anna’s creative director aide, is seriously the best person for the role.

Anyone editing a magazine for decades will make some mistakes (and I certainly did – most regrettably, I had Harvey Weinstein sitting in pole position at several dinners), so it’s not surprising that Anna has made her share of bad calls, including running an interview with Asma al-Assad, wife of the Syrian dictator Bashar al-Assad, and a blind devotion to the controversial John Galliano, who lost his job at Dior in 2011 for anti-Semitic remarks.

It’s undeniable her departure creates a small chink in her previously impenetrable facade of power at Conde Nast.

It indicates that there will be a time when she won’t be pulling any of the strings. I wouldn’t bet on that being any time soon, but even Anna is unable to control the rumour-mongering about why this change has happened.

Has she left that role of her own volition, recognising that there is a time to hand over the reins to younger talent?

Or has she been nudged by a board aware that investing so much power in one person, let alone someone of 75, puts the company in a vulnerable position?

The day my successor was announced was more difficult than I had expected. Anna wrote me a very sensitive email saying it must be an emotional day. I don’t think I had been aware of quite how quickly ‘le roi est mort, vive le roi’ (the king is dead, long live the king) kicks in.

Even though you’re still in the job, you are yesterday’s news.

My then 22-year-old son had left our house that morning for a short holiday in France. It felt like the whole of my world was trickling away.

So who will be the new head of editorial content at US Vogue? Currently it is thought Chioma Nnadi, currently in charge at British Vogue, could be in the running alongside other Vogue stalwarts such as US Vogue contributing editor Chloe Malle (daughter of late French film director Louis Malle and American actress Candice Bergen) and one of Anna’s favourites, Amy Astley, once at Teen Vogue and now in charge of American Architectural Digest.

All are talented characters and all are guaranteed not to go into battle against Anna. She will be aware of what happened when Enninful used British Vogue to build his own profile and clearly considered himself in pole position to succeed her.

The day I finally left Vogue was a Friday and I was going to Scotland with friends. My office was empty – my photographs, books, personal memorabilia, even a rug, had been packed away. It was a sad, barren place.

I couldn’t face another big leaving moment and had hoped to scurry out quietly, but others felt differently and as I wheeled my weekend suitcase to the lift, I discovered the whole staff lined up in the corridor, to clap me out in old Fleet Street tradition.

Once inside the lift I burst into floods of tears and was scarcely able to see the car waiting outside Vogue House. I had been editor-in-chief of Vogue for 25 years. Who on earth was I now?