Britain’s phone hacking inquiry has landed its second big fish, and it’s a whopper.

Late last night Andy Coulson — former editor of the News of the World and ex-head of communications for British prime minister David Cameron — was charged with the serious crime of perjury. If convicted he could face a heavy prison sentence.

Coulson was arrested in south London at 6.30am yesterday by seven detectives knocking on his door, and driven nine hours north to Govan police station in Glasgow.

He was charged there because he is alleged to have lied on oath in the trial of a Scottish politician Tommy Sheridan, who was jailed for three years for perjury in early 2011 (perhaps, partly as a result of Coulson’s evidence), and who has spent some of his sentence in Glasgow’s notorious Barlinnie Prison.

Perhaps that will be Coulson’s fate as well.

Sheridan had originally sued the NotW for defamation and won 200,000 pounds in damages after the Sunday tabloid published stories in 2004 of him attending swingers parties. He himself was then charged for concealing evidence from the court.

Coulson appeared as a reluctant defence witness for Sheridan, and was questioned for two days about his knowledge of phone hacking by the paper. By this time, Sheridan had obtained documents showing his phone had been targeted by the NotW’s pet private investigator, Glenn Mulcaire, who was jailed for phone hacking in January 2007. No doubt this is where the newspaper got the story.

Coulson repeatedly denied knowing anything about this, denied knowing, meeting or even hearing of Mulcaire until his arrest, and denied that phone hacking was endemic at the paper he edited from 2003 to 2007. “I don’t accept there was a culture of phone hacking at the News of the World,” he told the jury. “There was a very unfortunate, to put it mildly, case involving Clive Goodman. No one was more sorry about it than me; that’s why I resigned.”

It was News International’s trusty “one rogue reporter” defence yet again.

At the time he was telling these porkies, in December 2010, Coulson was still the PM’s media chief at No. 10 Downing Street. And this will put David Cameron under yet more pressure, because he told the House of Commons last July: “If it turns out that I have been lied to [by Coulson, regarding phone-hacking] that would be a moment for a profound apology. And in that event I can tell you I will not fall short.”

It was Cameron, remember, who picked Coulson as his media guru after the editor resigned from the News of the World in January 2007, when phone hacking was uncovered on his watch, accepted assurances from Murdoch’s man that he knew nothing about it. That is looking like an increasingly damaging decision.

So what might Coulson go down for if he’s convicted? One would think the sentencing judge would start looking at three years, given that’s what Sheridan got. This is more than anyone would be likely to get for simple phone hacking, where further charges against Coulson now seem sure to follow.

Once again, as in Watergate, the cover-up is worse than the crime itself.

Tommy Sheridan has so far made no comment about the Coulson charges, but last May he wrote to phone-hacking crusader Tom Watson to say “several of their [News International’s] senior executives and former executives should face prosecution”.

The letter (which is published in the MP’s book Dial M For Murdoch) went on to say: “My appeal is being processed and may bear fruit, but whatever happens to me personally is less important than ensuring the Murdoch empire is exposed for its criminality.”

And his final thought? “Murdoch himself must not be allowed to assume the role of Pontius Pilate in this whole sorry affair.”

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