It was all going so well. After years battling the public perception that something was a bit fishy, the Oscars once again – for a few hours at least – smelled of roses.

This year had been perhaps the hardest on record for the beleaguered Academy management. Against the backdrop of an endless battle to convince the public its members weren’t endemically prejudiced came a series of high-profile decision reversals in response to a string of massive backlashes. As D-day approached, so too did an ominous sense of vertigo.

Spike Lee on Green Book's Oscar win: 'The ref made a bad call' Read more

But within minutes, the mojo seemed to have been relocated. Sure, there was no overall emcee, but many of the presenters (step forward Tina Fey, Amy Poehler and Maya Rudolf) managed more laughs in two minutes than some awards-show hosts (step away, Joanna Lumley) elicit in a whole set.

The pairings who papered over the cracks and dished out the prizes often felt random (Helen Mirren and Jason Momoa) or their banter baffling (Daniel Craig and Charlize Theron). But none bombed; no one hired for the night was as unprepared as, say, the team who won best makeup for Vice.

The presenters were also conspicuously diverse, with 29 of the 52 non-white. In a year that saw landmark victories for black women in technical categories, the Academy was making an obvious but admirable bid to give airtime to people of colour.

New heroes and old history lessons: six key moments from the Oscars 2019 Read more

It worked. Finally, they looked in step and progressive. At last, light at the end of the tunnel.

And then Green Book took best picture. Yes, there were clues this twist was coming: Mahershala Ali winning best supporting actor despite Richard E Grant’s best efforts to woo voters. (though Ali had been the front-runner for yonks, so it was not a surprise, as such.) The Oscar for best original screenplay you could theorise was a sop to those fond of the film.

But to award a movie whose take on race relations seems more suited to its 60s setting than 2019 was an extraordinary final-reel slap in the face from this hitherto impeccable ceremony. More than that, it undid all the efforts that had come before.

Small wonder Spike Lee exited the auditorium as soon as the announcement came through, explaining later: “I was courtside in the Garden. The ref made a bad call.”

Green Book is often touted as the story of a white and a black man becoming friends despite their disparate experiences. But the worldview of its forever sympathetic protagonist (his son co-wrote the script) begins with him so racist he bins in disgust two glasses that a couple of African-American plumbers have recently drunk from. The “character arc” of Tony Vallelonga – AKA Tony Lip – is that of the classic white saviour: he helps his stuffed-shirt pianist employer DC Shirley avoid a beating before explaining to Shirley that he, Vallelonga, is “blacker” than Shirley because he likes Little Richard and Aretha Franklin.

This is not a different viewpoint: this is entrenched. The film’s bias is fundamental and it feels like a period piece in its psychology as well as its vintage cars.

Those in charge at the Academy cannot control the tastes of its voters. But they must be kicking themselves for this colossal act of self-sabotage. And if they don’t, it’s certain most of the audience will be up for putting the boot in.