If last Sunday evening’s broadcast of Steve McQueen’s Mangrove had gone out twenty years ago it would have given rise to a water-cooler moment the following day. Only a year beforehand the Macpherson inquiry concluded that the Metropolitan Police had been institutionally racist in its investigation of the 1993 murder of the black teenager Stephen Lawrence.

Unfortunately, the broadcast of Mangrove, which deals with the police racism leading to a protest in 1970 – and a subsequent political trial of nine defendants – coincided with the first opportunity to binge-watch the latest series of The Crown. If anyone missed Mangrove, they should catch up with it on BBC iPlayer.

“Apparently every last Jane Austen scribble had to be adapted five times over, and every serial killer needed his own three-part character study, before we got around to it,” complained Guardian television writer Ellen E. Jones.

Well, she has a point. The notorious Chicago Seven trial took place at around the same time as the trial of the Mangrove Nine, albeit on a much larger stage. Since then it has spawned several dramatizations including Aaron Sorkin’s The Trial of the Chicago Seven, which was briefly released in cinemas in September before a Netflix release in October.

The trial of the Mangrove Nine is a Black British story that deserves to be told and it receives measured and subtle treatment from the Oscar-winning director of 12 Years a Slave, Steve McQueen, who grew up steeped in the folklore of London’s West Indian community.

Indeed, a recreation of the mini-riot on Portnall Road, in front of the then Notting Dale police station, provides the climax to Trinidadian Horace Ové’s 1976 film Pressure, from a script by the Trinidadian novelist Samuel Sevlon, which was produced by the impeccably liberal BFI but not released until three years later because of its controversial depiction of police brutality. (Both Ové and Sevlon were Trinidadian immigrants, like Crichlow and Howe.)

Back in 1968, a small detail of beat policemen from Notting Dale police station’s Vice Squad begin to harass the Mangrove, a West Indian restaurant on All Saints Road in Notting Hill, which was the scene of riots against Caribbean immigrants by white Teddy Boys a decade earlier. Enoch Powell has just made his infamous “rivers of blood” speech and the West Way elevated dual carriageway is nearing completion.

The police are as ‘crooked as a damned ram’s horn’

The main characters are Frank Crichlow (Shaun Parkes), a Trinidadian restaurateur who just wants spicy West Indian food and is quick to banish any drug-users; Radford “Darcus” Howe (Malachi Kirby), a young Trinidadian radical lawyer, who is a disciple of the writer C. L. R. James as well as a Black Panther; Howe’s Black Panther girlfriend Barbara Beese (Rochenda Sandall); and Altheia Jones-LeCointe (Letitia Wright), another Black Panther and a trade union activist. Crichlow is set apart from the other three because he eschews politics, but Howe tells him he embodies the sort of leader who emerges from among the ordinary people under the pressure of events.

Although this is a political film, with three Marxists among its heroes, McQueen carefully skirts discussion of ideology. In one scene Beese berates Howe for lounging on the sofa reading C. L .R. James’s The Black Jacobins (about the Haitian revolution of 1791-1804) instead of clearing up the mess he has left in the kitchen.

Notting Hill is the fiefdom of PC Frank Pulley (played with smug menace by Sam Spruell), who operates out of Notting Dale police station. He is a bully and a thug, who is convinced that Crichlow is setting himself up as some sort of “chief”. He resents the Mangrove serving West Indian rather than English food, and even enjoys playing a game of cards with his fellow coppers in which the person dealt the queen of spades must immediately go out and arrest the first black man he sees without any pretext.

PC Pulley sees all West Indians as “savages” and “black bastards”, and he pursues Crichlow with an irrational obsessiveness reminiscent of Inspector Javert pursuing Jean Valjean in Victor Hugo’s Les Misérables. The Mangrove is soon raided on suspicion of being a nest of “criminals, ponces, and prostitutes”. The local council, magistrates, and the police are all work together to rob him of his drinks licence and frighten off his clientele. The police are as “crooked as a damned ram’s horn,” says Crichlow in a memorable phrase from the script co-written by McQueen and Alastair Siddons.

After the first police raid, McQueen cuts to a close-up of a nineteenth-century photograph of a black man, then cuts back out to a shot of the photograph, with the caption “Paul Bogle”, mounted against mangrove-printed wallpaper. Any Jamaican will know who Paul Bogle was – a Baptist deacon who led the Morant Bay protest against the colonial authorities in 1865 and was later hanged for fomenting rebellion. He is now celebrated as a national hero in Jamaica. Each shot lasts four seconds.

Another police raid ends with the viewer being left alone in the empty restaurant watching a colander gently rocking from side to side on the floor. McQueen knows to let the camera dwell on this image for longer than would be usual, as if to underline the shocking nature of the scene we have just witnessed.

Other grace notes are slow shots of the painted interior of the dome of the Old Bailey, with its inscriptions to ART and TRUTH, accompanied by a brooding, sliding strings chord. McQueen uses shots like this as a form of ironic punctuation between scenes of legal chicanery. At another point, in order to propel us through a trial that lasted 55 days in real time, he uses a rapid montage of still images showing the construction of the West Way and the transformation of West London.

The charges of riot and affray against the nine defendants had been dropped by a local magistrate but were reinstated by the Director of Public Prosecutions (Sir Norman Skelhorn, QC). The trial was conducted at the Old Bailey, which was normally reserved for cases of murder, terrorism and treason. Since the DPP had made this into a political trial, Howe and Jones-LeCointe opted to defend themselves, which allowed them greater latitude to run a political defence.

The court case begins in minute 52 of Mangrove and lasts until minute 121. Crichlow’s barrister, Mr. Croft expresses his sour view of the young radical barrister Ian MacDonald, with verbal challenges but also with a combination of looks and body language. Alex Jennings catches the defensiveness of the trial judge, Edward Clarke, perfectly: he is not a monster, but a stickler for convention and procedure in what he insists on calling “my courtroom”. Sam West, as the chief prosecuting counsel Michael Hill, conveys his patrician contempt for the defendants with a supercilious curl of lip or glacial shift of eyebrow.

Every courtroom drama needs its “gotcha” moments and here they come when Howe cross-examines PC Pulley and his three junior policemen about how they were each able to watch a couple of the defendants through a narrow observation panel. Pulley is then banished from the courtroom when he is seen communicating by hand signs with another policeman in the witness box. Accused of having bitten a policeman, Altheia Jones-LeCointe (Letitia Wright) scores another hit when she cross-examines an Asian forensic scientist and forces him to admit that his examination of the policemen’s skin four days after the event could not have any evidentiary value.

There are moments, too, of emotional power. When Jones-LeCointe overhears Crichlow discussing a possible guilty plea (and therefore a more lenient jail sentence), she confronts the restaurateur. He questions why the defendants are bothering to fight against a legal establishment that is dead set against them and she retorts “for my unborn child”.

Another powerful moment comes when Howe and Crichlow are manhandled down from the court and into their holding cells. Crichlow’s explosion of rage against the “wicked men”, filmed partly looking upwards to his belly as he leans against the cell door, reminded me of Jake La Motta beating his head against the wall in Martin Scorsese’s Raging Bull. But then we see one of the brutish court officers in profile, looking through the cell’s observation panel, bringing a vertical finger up to his lips in a sign to be quiet. The guard’s power cannot be overcome by mere noise, he seems to be saying.

And a final powerful moment is Darcus Howe’s passionate summing-up speech, laced with the reiterative phrase “it’s closing time”, which wins him an ovation from the public gallery. He talks about the policing of Notting Hill having “something that was located somewhere in the stench of British colonialism” and about “the black community creating institutions that it needs”.

The police raids on the Mangrove persisted for the next eighteen years

I have only one minor criticism of the film’s writers. Crichlow had a white partner, Lucy Addington, who was the mother of his three children born in the 1980s. In an early scene we glimpse a white woman who gives him a sidelong smile in the restaurant, and later, midway through the trial, he is anxiously contemplating his fate, smoking at a window, when a white woman appears and asks him to come back to bed. Was this Addington or an earlier white lover? She never comments on the trial, which is puzzling, and we are robbed of what must have been an intriguing perspective.

When the not guilty verdicts of the three principal defendants are read out, McQueen focuses on Crichlow and we truly feel the actor’s tears as the burden is finally lifted from his shoulders. Thankfully, there is no miscarriage of justice – as there would be a few years later for the Guildford Four and Birmingham Six.

The jury, with only two black jurors among them, dismiss the prosecution charges of riot and affray, though some of the defendants are convicted on lesser charges, and the trial judge reproves the “racism on both sides”. That sounds mealy-mouthed, but that is what he actually said and at the time it was considered a huge concession of defeat by the establishment that a judge should criticise the police in this way.

Nonetheless, the most shocking moment comes right at the end, with the epilogue titles. We have just witnessed the celebration party at the Mangrove following the verdict, but the titles explain that the police raids on the Mangrove persisted for the next eighteen years, only ending when the Met paid Crichlow compensation of £50,000 in 1989, the highest compensation they had paid to anyone at that time.

Today, Crichlow and Howe are dead, while Beese and Jones-LeCointe are still going strong. But whatever happened to PC Frank Pulley, the copper who gave Crichlow and the Mangrove such a hard time and whose name still invites scorn in Notting Hill today? He joined the Met in 1954 and retired around 1980.

After the trial, the Sunday edition of the People newspaper (with a sale of six million) ran a front-page headline that read “The Good Policeman Pulley”. This was sarcastic and within its pages the paper recommended that Pulley should be transferred: “He is the object of such widespread hostility that his effectiveness as an officer in this area with its special problems is gravely prejudiced.” However, in 1972, he won a libel action against the People newspaper over its depiction of him and was awarded £5,000 in damages and costs.

There is a Frank Pulley – retired, Metropolitan Police – listed on LinkedIn, which comes at the top of the page when you do a Google search. If still alive, Pulley would presumably be in his late eighties and I suspect he would have been watching The Crown last Sunday, not Mangrove. More’s the pity.