For viewers of television, What Happened Next? is the name of a famous round in A Question of Sport, but it's also a question which we tend to ask about famous dramas. A good piece of fiction should leave you eager to know what happened to the characters afterwards.
These narrative hangovers were entertainingly addressed by a recent Radio Times feature in which scriptwriters offered codas to famous sitcoms: imagining the later years of Captain Mainwaring, Mrs Slocombe, Steptoe & Son and Rigsby. Now the game is played for real in Prime Suspect 6 - The Last Witness, in which Helen Mirren, after a seven-year gap, returns as detective Jane Tennison.
Her journey initially seems small. Whereas the staff of Grace Bros ended up running a country hotel and the Dad's Army crew renovated a seaside pier, Tennison is still a guvnor in the murder squad, though working in London rather than Manchester, a switch set up by the end of the previous series.
And, although Jane never says anything about it, her dialogue has undergone a shift as well. At the beginning, it came from series creator Lynda La Plante but now it's a different guy each time: currently Peter Berry, who dramatised The Luzhin Defence.
To the credit of Mirren, there's a genuine sense of time having passed since we last saw her. The opening moments feature her Met medical, with much comment from doctors on her physical decay. She's even asked her age and - though knowledge of Hollywood chronology makes you brace yourself for Mirren's "41" - she boldly speaks out: "54". In the second scene, her superiors suggest that it's time she retired.
While there are actresses who wouldn't have risked this, Mirren's canny enough to know that the tactic may work to her advantage. We're supposed to squeak back "54?" and brand those characters who seek to remove her from the force as dinosaurs. But the honesty also holds a warning for ITV1. If Tennison is going to age in real time, then they're only going to be able to offer advertisers perhaps one more instalment before the franchise dies, although there are hints of other characters being fattened for a spin-off series: perhaps Mark Strong's DCS Larry Hall.
A male Prime Suspect, however, would lose the original distinction of this series, which is Tennison's gender. In fact, there are signs in this sixth outing that the character wasn't quite given enough depth to sustain what is now (given Prime Suspect's 2 x 120-minute format) 24 hours of television drama.
Inspector Morse had his Wagner, his ale, his crosswords, his loneliness and his son-substitute relationship with DS Lewis. Tennison's single signature characteristic from the beginning was that she used a different loo from the rest of the station. Now that her gender is less of a novelty both in society and the context of the series, Mirren sometimes seems short of much to do except tilt her head to one side and look with penetrating sympathy at a witness.
The main development in real-life policing while Prime Suspect was off-air was the Macpherson report, and Berry's script draws strength from this, substituting institutional racism (although La Plante touched on this in an earlier storyline) for the institutional male chauvinism that powered Tennison's first outings. This latest storyline involves the deaths of two Bosnian illegal immigrants and there's a subtle running gag in which even the office liberals like Tennison can never quite pronounce the Blekics, Lucics and Zigics who make up the lists of victims and suspects.
The director Tom Hooper, who often filmed Manchester in Cold Feet, seems happy to be in London and achieves a contemporary Dickensian feel: all hiding spaces under floorboards and floodit playing fields at night. Even so, on this evidence, Prime Suspect should bow out gracefully with its tally of six of the best.

Submitted by Kay