The inside story of the day Holly Willoughby sensationally quit – and why her mentor on This Morning was the LAST to know

As the offices look, it is hardly known for its library-like atmosphere. But shortly after 5pm on Tuesday, the bustling production studio at This Morning headquarters fell completely silent.

Cause? Holly Willoughby’s resignation letter, which just surfaced on Instagram.

The daytime TV star opted for a brutally public goodbye on social media, rather than a more traditional letter on the wall or a circular internal email – and the show’s loyal and hard-working staff were at a loss for words.

Holly’s move, of course, follows a tumultuous period on the iconic programme, which peaked last week when an alleged plot to kidnap and murder her was revealed.

And while some staff wondered if Holly would ever return to the TV couch that made her name, her decision to leave was shrouded in such intense secrecy that her Instagram post was the first they’d heard of her departure.

Silence in the production office was soon followed by tears — which weren’t necessarily triggered, insiders say, by the thought of losing Holly.

Indeed, many employees report that they have become less sympathetic to their chief executive in recent months.

No, their tears were caused by more drama and trauma behind the scenes. Many of the staff and crew have worked on This Morning for more than a decade and here is another crisis that would leave them picking up the pieces.

In short, they felt like Holly had been hung out to dry this morning.

“It was one after another,” one told me. “It’s like a soap opera and that’s fine if you’re one of the high-paid stars who commute, but if you’re grafting behind the scenes to keep things afloat, it’s incredibly frustrating.”

“Holly decides to go, she posts it on Instagram. Imagine how that makes you feel. There were tears. The team has been through so much in the last year. Many feel that they are at the end of their relationships. It was heartbreaking and difficult to watch it all happen.’

That word “all” refers to the seemingly endless controversies that have engulfed This Morning over the past year: last year Holly and her former co-star Philip Schofield were accused of skipping the queue to see the late Queen lie in state in Westminster Hall, then argued over how to respond to the accusation.

Then Schofield admitted he had an affair with a much younger runner who worked on the show — and lied about it.

Staff have also withstood pressure to be questioned by external barrister Jane Mulcahy KC about the programme’s alleged toxic work culture.

As for the show’s editor, Martin Frizzell — who likes to be called Maverick as in Tom Cruise’s Top Gun character — remarkably, sources tell me, he was completely “left out” of the conversation.

Instead, Holly has spoken out to ITV’s head of daytime production Emma Gormley, over an alleged plot by Essex security guard Gavin Plumb to kidnap and kill her, and her future on the show.

In fact, despite Frizzell pinning her colors to Holly’s mast during her feud with Schofield – his longtime friend – the TV veteran found out she was leaving the show just 20 minutes before Holly’s 8.5 million Instagram followers did.

Former GMTV editor Frizzell received an unexpected phone call shortly before 5pm on Tuesday telling him his biggest asset was to stand down. He also learned that she had prepared an emotional statement in which she was preparing to reveal that she was leaving the show for herself and her family following an alleged and highly publicized kidnapping plot.

Her words, which were composed entirely without the help of her former ‘rock’ Frizzell, read: ‘This is such a hard goodbye, you are amazing and I will forever be proud of what we have done together. Thank you to everyone at ITV for your support.

“To every guest who sat on our sofa, thank you.” Most of all thanks to the wonderful viewers. You were so loyal, so supportive and the best company every day.

“It was an honor just to be a part of his story and I know there are many more chapters to this story.” Unfortunately, however, I now feel that I have to make this decision for myself and my family. I will miss you all very much.’

Frizzell – usually unfazed by the words of his colleagues – was stunned. He was convinced that Holly would be staying with this morning for the foreseeable future. Indeed, she has only just signed a new contract, which will see her annual salary rise from £700,000 to around £1m.

She also vowed to ‘save the show’ after those many scandals – albeit before learning of an alleged kidnapping plot that would have scared the crap out of anyone.

For Frizzell, it was perhaps the worst possible way to part ways with Holly, the former golden girl of television.

Yet all his devoted attention seemed to count for nothing. “Despite Martin’s loyalty to Holly, he wasn’t in her inner sanctum when it really mattered,” says a source close to the situation. “He stood by her through all the difficulties with Phil, and besides, it’s his show, but instead Holly was all about Emma.”

“Martin always spoke so highly of Holly. He adored her and was extremely loyal.

“ITV is saying he was told so late. It doesn’t seem overly respectful. What a way to treat an editor.’

As for Gormley, who overtook Frizzell after working for him at GMTV, she also kept Holly’s decision from him.

Perhaps predictably, the briefing wars have begun as all sides await the outcome of an external investigation into Schofield’s conduct. It was delayed two months to ensure a complete and correct probe.

One insider told me: “There is a lot of concern about the outcome, who will be appointed and what the consequences will be. It’s all become a bit dog eat dog.’

So what’s next for this morning? It seems more than fair to say that Holly’s departure has left her on decidedly shaky ground.

Bosses were recently boosted after hatching a plan to have Holly join host Ben Shephard, who they thought was the perfect replacement for Phil.

Although no contracts were signed, it was otherwise a done deal, with insiders saying this morning that for the first time in a long time there was genuine excitement in the air that they had found television’s next big duo.

One said: ‘It was a dream.’ Now, however, bosses have been sent back to the drawing board – but with the added pressure of finding a woman to host.

Although they want to keep Ben — a reliable member of ITV’s daytime schedule who cut in for him on GMTV — they need to find him a partner with the necessary chemistry.

Although executives at ITV have been inundated with applications from presenters desperate to take Holly’s place on the sofa — complete with the fame and lucrative brands that potentially follow them — they know they have to get it right. Otherwise, the nine lives of this television cat will surely expire.

“One thing This Morning bosses didn’t think they’d have to worry about for a while was a female presenter, but Holly’s departure has changed all that.

“After she saw Phil off, they thought they’d have her for the long term.” She certainly made it clear that she was in it for the long haul, so this was really unfortunate,’ one source said.

Married couples are also apparently being considered, in the hope that they can recreate the golden years of Richard Medley and Judy Finnigan. The Voice host Emma Willis and her husband Matt, of the pop group Busted, are the subject of discussion, as is the female duo.

Despite all the worries the future holds, many unanswered questions still remain about Holly’s departure. Some wonder if the drop in ratings on This Morning also contributed to the pressure the presenter was under.

Despite the best efforts of ITV bosses, they have fallen to around half of what they were before Holly and Phil fell out.

Ratings for Holly’s return to the show alongside Alison Hammond in early September were as high as 565,000 compared to two million at its peak.

The star, who has often been described as ‘wise’, insisted he could turn things around. The bosses believed that she really wanted it, but they were afraid that it was all too much for her.

‘It was a huge task. Holly was all for it,” said a program insider. ‘She felt it was her duty to do so.’

However, she returned to some pretty harsh criticism on day one when she and her new best friend Alison, 48, danced together. And the next day Alison showed up to excitedly mount guest Jason Donovan on the show’s famous sofa.

The online attacks prompted Holly to launch a charm offensive at the National Television Awards, where she was booed by the audience this morning.

Despite not being shortlisted for best presenter for the second year in a row, she attended, friends say, for the sake of the show.

But, they add: “At that moment, she knew that things might not be easy.” Popularity has weakened everywhere.’

Meanwhile, Holly’s former colleagues wonder what she will do next.

Interestingly, she is yet to commit to her second ITV show, Dancing On Ice, while the BBC is reportedly ready to pounce after years of desperate to land her for one of its big shows.

For now, however, she is adjusting to life as a stay-at-home mom with her three children, Harry, 14, Belle, 12, and Chester, 9.

But one question remains on the lips of This Morning’s loyal production staff.

When she’s ready, will the wily Mrs. Willoughby reinvent herself and take to prime-time TV?