Last week, as far as I can see, that venerable weekly magazine, The Spectator, accused Sir Ken MacDonald, the Director of Public Prosecutions, of perverting the course of public justice.

Let me give some context here, because in the same edition a book reviewer claimed, in all seriousness, that Tony Blair took us into Iraq to boost his prospective postretirement earnings on the US lecture circuit, so perhaps one shouldn’t take it all too seriously. Even so, this particular cover story by Fraser Nelson, the political editor of The Spectator, was notable because it gave the impression to the reader that the accusation against Sir Ken originated in the Metropolitan Police, somewhere not unadjacent to Assistant Commissioner John Yates’s cash-for-honours investigation.

During the inquiry, apparently, “the Metropolitan Police noticed something amiss. The 10 Downing Street officials they had interviewed seemed suspiciously well prepared.” How might that have happened? Well, Sir Ken was at a party where “it is believed” a Scotland Yard man was sounding off. “It is impossible,” writes Nelson, “to say with certainty whether this was the conduit for information back to No 10 or not, but it appears to have been all too much of a coincidence for Mr Yates.” Hardly surprisingly Sir Ken is angry about this “all-but-certain” allegation. He denies being at any party where such a discussion took place and, frankly, without a named source for the allegation or corroboration the whole thing looks like . . .

Well, what does it look like? The cash-for-honours inquiry has turned surreal for me. This year I will have been in the journalism business — TV, radio and papers — for a quarter of a century, and yet I have no way of evaluating most of the stories being published on the subject. When a report says “according to Whitehall sources”, I literally have no idea which agency, group or individual is speaking, and therefore I equally can have no idea why.

That’s the reason The Spectator article was so important, full as it was of phrases such as “the police are by no means satisfied that they were told the whole truth by Ms Turner”, “I understand that police have found substantial evidence . . .” and so on. This looked like the “Rozzetta” Stone, in which the hieroglyphics of private police briefing could now be turned into comprehensible concepts. If this was right, then the police were saying that the political bastards have probably successfully covered up evidence of the sale of honours, but in the process have perverted the course of justice, and that’s what we’ll be saying to the Crown Prosecution Service, and if the CPS don’t throw the book at someone for that then it isn’t our fault, guv.

Before I started writing this article I looked in the mental mirror and wondered if I would be writing this piece if it concerned the Liberal Democrats or Tories. And, though it may sound unconvincing, I decided I would. But increasingly when writers (as Nelson did) invoke Watergate and the fatal cover-up, I begin to think of Whitewatergate, the six-year long investigation into supposed Clinton corruption, that ended without prosecution after costing the US public more than $75 million.

More than a year ago a complaint caused the police to dust down their copies of the Honours (Prevention of Abuses) Act of 1925. Had the Government (or the Conservative Party) sold honours in return for party donations or loans? But there was a problem here, in that the parties had always factored in donations as a possible part-qualification for honours. And they had done it overtly. In May 1998 Lord Pym, a former Tory Cabinet minister, who chaired the Political Honours Scrutiny Committee. appeared before the Neill Committee on Standards in Public Life. “If someone gives their money to a party,” Lord Pym said, “I would regard it as a plus rather than a minus point that people put their money where their mouth is.”

That was Margaret Thatcher’s view. Between 1979 and 1985 she ennobled 11 industrialists, all of whose companies had donated money to the Conservative Party, to the tune of nearly £2 million. Nor has Mr Blair ever denied that party donations were a factor in honouring certain people. If Yates et al weren’t to investigate the Major and Thatcher years and then as far back as the statute of limitations, it would seem arbitrary to begin with this Government, unless you had clear evidence that someone had said to someone else: “If you give us this money we will give you a peerage.”

It may be, I suppose, that such evidence exists, and that the deployment of the second possible charge, perverting the course of justice, is a justified ploy to “smoke out” this evidence. Or maybe not. The CPS says this charge should be reserved for “serious cases of interference with the administration of justice”: intimidation or interference with witnesses, interference with jurors, making false alibis, giving false details of identity, concealing or destroying evidence, assisting others to evade arrest, or making a false allegation.

In its guidance of when it is appropriate to use this charge, the CPS’s guidelines says one test is when “a police investigation into serious crime has been significantly or wholly frustrated or misled”. In the Spectator article Nelson says this of Yates. “He did not bargain for the barrage of half-truths, obfuscation and outright obstruction his detectives have encountered.” A sentence better and more exactly designed to meet the needs of the CPS guidelines would be hard to imagine.

Now, I think that the attempt by the two major parties in 2005 to subvert the rules on transparency by organising loans rather than taking donations was crass and reprehensible. That isn’t the same as illegal, yet I think some people long ago decided that it should be, and that someone should get sent down for it, just like Aitken or Archer.

After first reading The Spectator I thought that the drive behind this may be rooted in a police desire not to look like Dixon of Dock Green crossed with Kenneth Starr. Other journalists have convinced me that I may be doing the police an injustice, and that some of this may well be the result of editorial pressure on reporters to produce exclusives beyond the evidence available.

Whichever it is, the results are serious. On Sunday night, in a silly moment of TV bravado I bet a fellow journalist that no one would be convicted in cash-for-honours. Then a viewer sent me an e-mail. You think a trial would be a judicial process, like Hutton, he said. But can you imagine what a jury, given the mood and all that has now been said and written and leaked, would do to a Tony Crony? It wouldn’t be a trial, he implied, it would be a by-election. I thought about it all night. He’s right.

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