What happens when you bring together Britain's former top policeman with two of its most successful crime writers?
Crime novelist PD James, one of the Today programme's guest editors, persuaded the former Met commissioner Sir Ian Blair into a studio with fellow crime novelist Lynda Le Plante to discuss the realities of crime fiction.
Sir Ian Blair has a bit of a problem with crime fiction, especially on television.
A friend of the Morse author Colin Dexter, he quips that after reading Dexter's books "nobody is going to want to be a head of house in Oxford: the average life expectancy is about three weeks".
But it's not just the rarity of murder which exercises the former head of the Met - he quotes figures indicating that there are just 130 killings a year in London, a city with a population of eight million - but the frequency of "heavy violence" in crime fiction.
Crime drama is unrecognisable from the days of Sgt. Dixon
"The more we see of this the more people are going to be afraid that is what happens so often. And it doesn't happen that often," he adds.
Beyond this, he believes that on-screen representations of court cases can blur reality, "because evidence that would be acceptable on CSI doesn't exist in the British court room.
"As always, literature is a part of art and it mimics real life, but it's also slightly behind the curve."
Sir Ian says that the "Nova Scotia effect" is partly to blame for the UK's fear of crime.
"The murder rate in Nova Scotia and in Great Britain is about the same per head of population," he says.
"That's because in Nova Scotia, you only hear about crimes that are either committed in Nova Scotia or that are so appalling they are on CBS News.
"Whereas here, whether its in Aberdeen or Aberdovey, you hear about every incident that happens in Britain... Statistically it is still very rare, that doesn't make good drama."
"Order out of disorder"
Crime fiction is "slightly behind the curve" according to Sir Ian Blair
Crime writer Lynda La Plante, the woman behind Prime Suspect, Widows and Trial & Retribution, doesn't worry about violence. "I suppose I should. Every time you open the paper there's another horror," she admits.
But she sees that, by showing there is a conclusion, crime fiction plays a very important role. "Case closed. One is successful in bringing horrendous perpetrators to justice."
For Sir Ian, the representation of what goes on in court remains problematic. "There is actually a thing called the CSI effect." he reveals.
"Juries don't understand why in this particular case no forensic evidence has been brought forward. That is because in routine cases the police use very little forensic evidence because it is very expensive to do."
In reality, he says, detective work can be quite boring.
"Sometimes I find [CSI] almost laughable," La Plante smiles. "Because you see the woman with long blonde hair - she looks about 18 - she's one minute a ballistics expert and the next minute she's doing virtually a pathology test.
"Whereas in forensics when they go into a cadaver they are gowned up for a reason, they are shedding hairs, they are shedding fibres. Whereas this girl is swishing her hair back from her face and they're leaning over the body having great conversations over the cadaver, its very unreal."
Lynda La Plante finds some of CSI to be "laughable"
PD James, whose novels featuring the poetic detective Adam Dalgleish have delighted millions of readers, is quick to stand up for the detective story, as opposed to the crime novel, for "bringing order out of disorder".
"You don't in the end really get justice, because you only get the fallible justice of men, you don't get infallible divine justice, you get the best of which you are capable, but you do get a conclusion, and you do get an ending."
La Plante agrees: "The truth is, we have had a litany of crimes recently that do beggar belief. When you do have horrendous crimes covering the front page sometimes you think about it.
"Over and over again, we are faced with horrors. To me, the closure is of great importance. So I will continue to write crimes that I see in the paper."
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