It was surprising yesterday to hear Radio 5 Live invite News of the World investigative journalist Mazher Mahmood into their studios to puff his recent book. Simon Mayo’s show is usually more discerning.

Starting with a fatuous charade to obscure Mahmood’s identity, the lights in the studio were dimmed so that those viewing through the webcam wouldn’t see his visage, despite that fact that it can be seen on several well-used websites, including Wikipedia.

You might ask - Who gives a shit anyway? The man’s a busted flush. His brand of sloppy, largely fictitious journalism is less in demand than it was as the GB Public become more sophisticated (not enough yet, though; over 3 million morons still buy the News of the World every week to grubby up their Sundays.)

But is it the BBC’s function to give a platform to a man who has been branded totally untrustworthy in frequent court hearings, who can be shown to have set up – even cast like a B-movie director – a string of stories that on closer inspection have little, sometimes no basis in reality at all?

Mayo did nothing to challenge a number of Mahmood’s claims. He didn’t question the specious statistics he bandied around – the number of ‘criminals’ he claims to have been responsible for bringing to justice, which includes busloads of illegal immigrants cheated by people traffickers and turned over by their lawyers. He didn’t ask him about the shocking stories he’d spun out of nothing, leaving several innocent people in jail for up to 2 years, like the ‘Beckham Kidnap’ and the ‘Red Mercury Scare’, although a quick glance through my recent book, News of the world? Fake Sheikhs and Royal Trappings would have given him plenty of ammunition.

Mahmood didn’t achieve the notoriety he has by not being very skilled in convincing people of other than the truth, but Mayo was unprepared and walked straight into a quicksand of disingenuous charm and bullshit. Why didn’t Mayo ask Mahmood how many of his books have been sold? Barely plugged by the News of the World after a lack-lustre launch by its stable-mate, publishers Harper Collins, it has made a very poor showing in the bookshops.  Didn’t this strike Mayo as odd, given the profile of the Screws’ ‘Investigations Editor’? Are they embarrassed about it – its content or the relentless self-congratulatory journalese in which it is written - or the liability the man himself has become?

Mazher Mahmood is demonstrably one of the principal elements in the demise of truth in modern British journalism. Following the BBC’s own struggles with authenticity over the last year, it’s inexcusable that they should now be supporting his efforts.