Age: Classified.

Appearance: I could tell you, but then I'd have to kill you.

Is there anything you can tell me that won't result in someone dying? Yes.

What is it? It's complicated. Are you familiar with Sgt Danny Nightingale?

The 38-year-old SAS sniper who was given a suspended sentence after being convicted of keeping a Glock 9mm pistol and various rounds of ammunition in his house by a court martial in July, which was held after the court of appeal overturned a previous conviction for the same offence? I'll take that as a yes.

Good idea. Well, during the recent retrial, "Soldier N" was the codename given to a former colleague and housemate of Nightingale, who testified that it was routine for soldiers to bring weapons back home as trophies.

I see. But the court heard allegations that Soldier N was an unreliable witness. One piece of evidence was a letter that his parents-in-law had written two years ago to a commanding officer in the SAS, in which they said he was behaving erratically.

I'm with you so far. Good. The letter said that Soldier N was scaring his children by hoisting them high up in trees and transporting them around under canvas in the back of his Land Rover, and that he was frightening his wife with threats to make her "disappear".

How allegedly horrid. Quite. The letter also claims he said that Princess Diana had been murdered by the SAS.

Proof at last! Except it's not quite proof, is it? An inquiry and an inquest both found no evidence at all that Diana was killed deliberately. Needless to say, during the silly season, the world's media have jumped on the story.

I noticed. So this "Diana killed by SAS" thing was mentioned precisely as an example of something that an unreliable person would say? Basically.

But the media are reporting it like it's significant? That's right.

Honestly, some people will print any old rubbish to sell newspapers, won't they? They will indeed.

Do say: "Perhaps we should just have a Diana inquiry every four years? A bit like the World Cup."

Don't say: "The guy who works in the pet shop where my wife's friend used to buy cat litter is the same age that Lord Lucan would be today."