“Cop shows have conditioned us to believe that police detectives are all brilliantly clever and committed,” says Stephen Merchant. “On screen they’re like dogs with a bone, they don’t let any leads drop.”

So when the 47-year-old writer, actor and comedian who first came to prominence in 2001 as the co-creator of The Office was first approached to play serial killer Stephen Port in the BBC’s true crime drama Four Lives by Jeff Pope and Neil McKay, he was “really unsettled, really upset” to discover how long it took for the Metropolitan Police to arrest Port. “When I first read the script,” he says, “I wanted to believe that some of the many police errors in the investigation must have been overstated for dramatic purposes.” He shakes his head. “But they weren’t, were they?”

Dubbed the ‘Grindr Killer’, Port used the gay dating site to target younger men. He administered fatal doses of the “date rape” drug GHB to Anthony Walgate (23), Gabriel Kovari (22), Daniel Whitworth (21),and Jack Taylor (25) then dumped their bodies near his flat in Barking. In fact, he left Walgate (a popular fashion student) directly outside his flat, and the three other bodies in the same church yard. Despite many similarities and repeated questions from the victims’ families, the police failed to link the deaths.  

Last month an inquest jury concluded that fundamental failings in the Met’s investigation of Port’s victims “probably” contributed to three of the four deaths. Earlier this month, a group of London MPs called for a public inquiry into claims of institutional homophobia.

Four Lives depicts Walgate’s mother Sarah Sak (played by Sheridan Smith) struggling with an appallingly offhand family liaison officer. We see police refuse to show the (faked) suicide note of Whitworth to his boyfriend, when Merchant argues that they would “surely have treated a heterosexual couple differently”.