Martha L. Ruiz and Brian Cullinan from PwC are responsible for the biggest Oscars blunder in history. Picture: AP

For each category of this year’s event, PwC executives Martha L. Ruiz and Brian Cullinan carefully placed a card revealing the winner into an envelope and sealed it.

Then they did it again until they had two full sets, in which the dreams of Hollywood’s elite could be made or broken.

Each set was placed into a black briefcase, emblazoned with the Academy’s gold triangle logo, and locked inside a safe.

The contents of those envelopes were known to no one but those two. It was meant to be a fail-safe system but as we now know, it wasn’t.

A team of PwC accountants helped count up to 6,000 ballots when voting closed on February 21, but it was done in a way so none were in the loop.

“Our teams work in small groups,” Cullinan explained to MarketWatch.

“We count up the smaller groups. They all only see a piece of it but never see the whole thing … it’s really only Martha and myself who ultimately know who won before the show.”

The two memorised every winner, afraid to write them down in case the list was misplaced.

Chaos on the Oscars stage after Warren Beatty and Faye Dunaway announced the wrong Best Picture winner. Picture: APSource:AP

No one had access to the secure storage space, which is actually a room inside a room with a safe inside a safe, except Ruiz and Cullinan, who returned late in the morning on Sunday.

“There’s a ton of redundancy and security built in,” he explained to Cornell’s alumni magazine.

They each took a briefcase and travelled separately to the Hollywood and Hyland Centre with a police escort, where they posed for photographs — Cullinan wearing a classic black tuxedo and Ruiz in a flowing red V-neck frock — while walking the red carpet.

Marta L Ruiz and Brian Cullinan lapping it up on the Oscars red carpet. Picture: TwitterSource:Twitter

Once inside the theatre, they took their positions on either side of the stage. He was on stage right, she was on stage left.

For Cullinan, the chairman of PwC’s US Board of Partners and Principals and a member of its global board, it was his fourth time doing this, and for Ruiz, a tax partner, it was her third.

But their excitement at being such close, special witnesses to the film industry’s night of nights was evident, with Ruiz sharing pictures from the red carpet.

Their colleagues Tweeted enthusiastically as they spotted the lucky pair in the background of live television shots. Even PwC’s normally stuffy Twitter account got in on the fun.

Even for bean counters like Cullinan who’s a specialist in the fields of entertainment taxation, the Oscars can leave one starstruck.

“A lot of times there’ll be a kind of reversal of roles where sometimes celebrities will come over to us and ask if they can get their picture taken with us, which is kind of funny,” he told MarketWatch.

He once recalled how in 2014 Australian actress Cate Blanchett playfully tried to swipe his briefcase, in which a card read her name in the Best Actress category for Blue Jasmine.

And there’s a running joke about his striking resemblance to actor Matt Damon.

Cullinan obviously loves this stuff. He has pride and perhaps even a bit of ego about his role as vote counter, describing himself in his Twitter bio as a keeper of Oscars secrets.

Yesterday, when Emma Stone won Best Actress for her role in La La Land, he took out his phone and snapped a blurry picture of her beaming with her statue backstage.

Brian Cullinan Tweeted a backstage photo of Emma Stone after she won the Best Actress Oscar but then quickly deleted it. Picture: TwitterSource:Twitter

He posted it to Twitter and then, moments later, quickly deleted it, perhaps sensing that it was inappropriate.

Was that on his mind just minutes later when he handed veteran actors Warren Beatty and Faye Dunaway the envelope for the final and biggest category of the night, Best Picture?

Was he gushing over having locked eyes with Stone, one of the hottest stars in Hollywood?

Or was he simply tired, nearing the end of another marathon ceremony?

Whatever the reason, Cullinan gave Beatty and Dunaway the wrong envelope — his duplicate of Best Actress.

Leonardo DiCaprio and Emma Stone, winner of Best Actress for La La Land. Picture: Getty ImagesSource:AFP

His colleague Ruiz had handed that category’s presenter Leonardo DiCaprio an envelope when he entered from stage left. Perhaps distracted, Cullinan hadn’t discarded his copy of it.

Second later, the orchestra having played them on, Beatty and Dunaway stood at the microphone in front of a crowded room of showbiz elite.

He looked confused and checked the envelope again, she playfully chastised him for keeping us all waiting, and so he handed the envelope to her.

“La La Land!” she said, and the theatre erupted into applause.

The musical about Hollywood had won the top honour of the night, and its cast and crew made their way to the stage.

PwC has vowed to investigate the error and has apologised to all involved. Picture: AFP PhotoSource:AFP

It’s probably at this moment that Cullinan and Ruiz felt their chests tighten. That wasn’t the winner. They knew it from their memorised lists of Oscars recipients, from those votes they’d tallied and the cards they’d stuffed in envelopes to make two full sets.

The winner was actually Moonlight.

“He took the wrong envelope!” someone screamed backstage, USA Today reported, as chaos erupted.

Stage managers, normally not seen by TV cameras, rushed out as La La Land’s producer Jordan Horowitz had just finished speaking. There were envelopes in hands, confused looks, whispering in suddenly devastated ears, and finally the error was realised.

Horowitz told the audience, and viewers, what had happened and the rightful winners were called up to receive their prize.

A sea of stars leaving the theatre a few minutes later, including Aussie star Nicole Kidman, remarked on the monumental and historic moment.

“It’s the craziest thing I’ve ever seen,” she said.

A shocked Oscars audience realises the mistake. Picture: APSource:AP

Several hours later, PwC issued a grovelling apology for the mix-up and promised to investigate. Cullinan, his boss Tim Ryan told reporters, was devastated.

“He feels very, very terrible and horrible. He is very upset about this mistake. And it is also my mistake, our mistake, and we all feel very bad,” Ryan said.

“We clearly made a mistake and once the mistake was made we corrected it and owned up to it.”

Mr Ryan spent the hours after the awards show speaking with Mr Cullinan, Ms Ruiz and members of the Academy and the show’s producers, the New York Times reports.

“I spent the bulk of the night with Brian trying to understand what happened,” Mr Ryan said. “There wasn’t much in terms of parties last night.”

La La Land producer Jordan Horowitz holds up the correct card that reveals Moonlight as the winner of Best Picture. Picture: APSource:AP

Ironically, Cullinan and Ruiz did an interview with the Huffington Post last week headlined: “What would happen if a presenter announced the wrong winner at the Oscars?”

They insisted such a snafu was highly unlikely.

What happens next is still in doubt, as their 83-year tenure as official vote counters is in threat.

Leslie Moonves, the chief executive of CBS, said in a videotaped interview after the show: “The accountants have one job to do — that’s to give Warren Beatty the right envelope.”

“That’s what these people are paid a lot of money to do. If they were my accountant, I would fire them.”

As Cullinan told MarketWeek, there’s no formal tender and either party can call it quits when they like.

“As long as our relationship is good and strong and we do a good job, which we always do, the academy has been pleased I think with how we’ve been involved.”

That probably isn’t the case anymore.