Inside No 9, episode 3, review: Fleabag's Sian Clifford hits the mark in Line of Duty send-up

The arrival of Fleabag’s Sian Clifford several minutes into the latest Inside No 9 (BBC Two) raised the fleeting possibility that Reece Shearsmith and Steve Pemberton were about to surprise viewers with the ultimate BBC crossover. Would Phoebe Waller-Bridge and Hot Priest Andrew Scott likewise burst through the fourth wall? Scott could have certainly done with a change in scenery having just been forced into a third-rate Adam Ant impersonation in Emily Mortimer’s over-ripened toff pageant The Pursuit of Love.

Tragically, this did not turn out to be the case. Instead, Lip Service proved a gripping if slightly formulaic plunge down the Inside No 9 rabbit hole. And far from plugging into the sort of arch social comedy at which Clifford excelled in Fleabag, Pemberton and Shearsmith were cribbing from the Book of Jed Mercurio. They even closed the instalment with a pivot straight out of Line of Duty or Bodyguard. It was fun, largely because the pay-off landed with such force.

Felix (Pemberton) was a sweaty, nervous loner convinced his wife, Brenda, was having an affair with her suave boss, “anti-government campaigner” Dmitri Novak. Driven to the brink, Felix hired professional lip-reader Iris (Clifford) to observe Brenda and Novak from a hotel window overlooking an office block. By parsing their conversation he hoped to establish whether they were lovers or merely colleagues. Much fun was had with reading - and misreading - their lips through Iris's binoculars.

Felix wasn’t really Brenda’s husband. They’d never married, the relationship was long over and she had taken out a restraining order. And Iris wasn’t a sweet and naive lip reader, as we discovered in the shocking denouement.

The only one who was actually the person they claimed to be was snoopy, Basil Fawlty-style hotel manage Eric (Shearsmith). He was convinced Felix had slipped a woman into the room for nefarious purposes. He was correct – but the reasons weren’t quite what he (or Felix) suspected.

Felix had been put in contact with Iris by a helpful poster on Dadchat – “Mumset only with sad men rather than competitive women”. However, it turned out that it was Iris herself who had planted the idea. She was an enforcer for the Government, her mission to frame Felix for the assassination of Novak before he could make highly damaging claims against Number 10.

A twist is only as good as its performer, and this one went off like a firecracker, Clifford selling it completely, dropping the shy librarian routine just as a gunman she had smuggled into the adjoining room shot Novak. She then tossed Felix a hair-dryer. Gazing out the window yelling at Brenda, he looked like a lunatic waving a firearm. Police marksmen took him down – and Iris slipped a gun into his hand. A political killing was passed off as a crime of passion by a jilted lover.

It was all massively Mercurio-esque – albeit with the bonus that you didn’t need a diagram to work out what had happened. The devastating conclusion even leaned into the idea of a deep state brimming with bent coppers and corrupt politicians. As the smoke cleared, the thought occurred that perhaps BBC should have drafted in Pemberton and Shearsmith to add pep to the underwhelming Line of Duty finale. With this episode, they showed they could at least hit the target.