Between the Lines is British television’s forgotten classic cop series. Its contemporaries – Cracker, Prime Suspect and Inspector Morse – are better known but, arguably, not as good.

Two decades before Jed Mercurio’s Line of Duty blew the lid off police corruption, Detective Superintendent Tony Clark (Neil Pearson), DI Harry Naylor (Tom Georgeson) and DS Maureen “Mo” Connell (Siobhan Redmond) from the Metropolitan Police’s Complaints Investigation Bureau were also hell-bent on nailing dodgy coppers.

On the surface, the corruption portrayed is often small scale; officers roughing up suspects or lining their own pockets. Unlike Line of Duty’s Anti-Corruption Unit 12, Clark and Co are not on the trail of an “H”, a senior officer in cahoots with organised crime.

Dig a little deeper, or read between the lines if you prefer, and racism, far-right extremism or violent misogyny are often behind the wrongdoing. Add some conspiracy – MI5 machinations and government skulduggery are to the fore – and you have the Between the Lines MO.

Series creator JC Wilsher had cut his teeth penning episodes of long-running ITV series The Bill, but Between the Lines was a very different proposition to that or TV’s other cop shows of the time. Its action is cerebral, rather than played out with car chases and shotguns; its morality is murky; and the bad guys often get off scot-free. Like real life.

Wilsher approached Tony Garnett, a producer with a radical track record, from Cathy Come Home and Kes in the 1960s to GF Newman’s 1970s crime series Law & Order, on the failings of the criminal justice system. Later, he would go on to make the groundbreaking legal drama This Life.

Garnett, who had recently formed World Productions, told the Independent that he had “had an eye on a police procedural” for some time before Wilsher approached him with a proposal about police corruption. “I knew it was a good idea… because I thought, ‘Why didn’t I think of that?’ It also meant that I could have bent coppers on every week.”

Between the Lines ran for three series on BBC, from 1992 to 1994. To lighten the political load, we see a lot of the team’s private lives. Tony Clark is a ladies man; it’s not for nothing that the show was dubbed “Between the Sheets”. It was a role Pearson was born to play – and one that he was also serving up brilliantly at the same time as the office Lothario in Channel 4’s sitcom Drop the Dead Donkey.

Mo Connell is bisexual – a rarity at the time on British TV – and has two serious relationships, first with a man and then a woman, both of which are entirely believable and sympathetically portrayed.

But Naylor is the heart and soul of the series. With a fag constantly on the go, he is a gruff, old-school copper, happy to cut a few corners if the end justifies the means. Yet, he never loses his moral compass, unlike the more ambitious Clark and Connell. His private life, until tragedy intervenes, is happy but humdrum. Has any other TV cop shone at ballroom dancing?

The final series, which saw the team drummed out of the Met and operating in the opaque world of private security, and often unofficially for MI5, slowly runs out of steam and credibility.

Series 1 and 2, though, are crackers, and snaffled awards from the RTS and Bafta. A few years later, Between the Lines made the BFI TV 100, a list of the best-ever British programmes.

And then it was pretty much forgotten, until 2021, when, in a clever, if belated, piece of scheduling, BBC Four aired it straight after the current series of Line of Duty. Better late than never.

All three series of Between the Lines are on BritBox.