'It doesn't sound very complicated': The words that will come back to haunt Brian Cullinan

"It doesn't sound very complicated, but you have to make sure you're giving the presenter the right envelope."

Those are the words that are surely going to haunt Brian Cullinan following the monumental stuff up at the 2017 Academy Awards that saw La La Land briefly called out as the winner of Best Picture before it was actually given to the real winner, Moonlight.

The lead partner for accountancy firm Pricewaterhouse Coopers made the comments in the lead up to the Oscars in which he said so far, there has "never been a problem" at the famous ceremony.

Fred Berger, producer of La La Land, foreground, gives his acceptance speech as Brian Cullinan, holding red envelope, and Martha L. Ruiz, in red, discuss the botch-up. Photo / AP

"The producers decide what the order of the awards will be. We each have a full set. I have all 24 envelopes in my briefcase; Martha has all 24 in hers.

"We stand on opposite sides of the stage, right off-screen, for the entire evening, and we each hand the respective envelope to the presenter. It doesn't sound very complicated, but you have to make sure you're giving the presenter the right envelope," he said.

Cullinan and his partner Martha Ruiz were the pair in charge of counting votes for the awards and the only two people to have known the result before the ceremony.

Their position has been described as the "coolest job an accountant can have" and it's no easy gig to get. Cullinan has 30 years experience and has been leading the ballot team since 2014 while Ruiz joined the team as co-leader in 2015 after 10 years behind the scenes.

Both of them had been excitedly tweeting behind the scenes news in the lead up to the event and conducting interviews with international television stations.

Ruiz has previously described handing out the envelopes as surreal and intense, saying
"I distinctly remember, after the last envelope was handed to the presenter, it was like a flashback - 'Wow that was great, that was exciting' - but as each minute was passing during the day of the show, I was laser-focused."

Faye Dunaway, from left, accountant Brian Cullinan, AMPAS staffer, and Warren Beatty discuss the result of best picture at the Oscars. Photo / AP

It's not known which of the two presenters handed the wrong envelope out, but PwC is investigating what happened.

After the gaffe, the company issued a statement saying they "deeply regret" what occurred and apologised to the producers, presenters, viewers and actors involved.