The lesson of the News UK scandal is not that journalists are bad. It's that corrupted journalism was so corrosive to democracy that only great journalism could save it.

We now know that phone hacking was rife at the News of the World. The jury found that even the editor, Andy Coulson, was involved in it along with three senior news editors.

There were over 1,000 victims and 6,000 hacked phone calls in a two-year period before the arrests of Clive Goodman and Glenn Mulcaire. And yet for years, the predecessor company to News UK, News International, claimed that hacking was the work of a single rogue reporter – surely the biggest corporate lie in recent history?

When the police, 95% of the media and successive governments failed, it was only fearless journalism that exposed the wrongdoing.

The criminal defence on show was the biggest and most expensive ever mounted in a case of this type. Murdoch paid for most of it. And he will be paying for civil cases for months to come. Phone hacking has cost his empire an estimated half a billion pounds to date.

Coulson's extraordinary conduct over many years shows how News International became so powerful it even managed to compromise the integrity of the prime minister. For David Cameron to appoint Coulson to Downing Street, bypassing all the usual vetting procedures, casts grave doubt over his judgment. At prime minister's questions today he claimed that all the difficult questions had been covered at the Leveson inquiry.

Yet at the inquiry, Cameron claimed that in 2009, when the Guardian first reported that phone hacking at the News of the World may have gone further than a single rogue reporter, Coulson said he knew nothing about it – repeating an assurance made on taking the job with the Conservatives. Under oath, Cameron said: "I was reliant on his word but I was also reliant on the fact that the Press Complaints Commission had accepted his word, the select committee had accepted his word, the police had accepted his word, the Crown Prosecution Service had accepted his word."

But at that point in 2009, Coulson had not been interviewed by the police, the CPS or a select committee on the subject, and the PCC never interviewed Coulson personally. The prime minister gave an explanation which was – wholly, demonstrably and in detail – false.

One of the most disturbing revelations throughout this period was that Tony Blair was the secret godparent of one of Murdoch's children. There was Tony, on the banks of the river Jordan, satin robes rippling in the breeze, genuflecting to the most powerful media oligarch on the planet.

And when it was revealed that poor Milly Dowler's phone was hacked, what was Blair's first reaction? It wasn't to ring Mrs Dowler. It was to offer to advise the company on their PR strategy. Like many others in the Labour party, I am ashamed of him.

There are more questions to answer. The dedication and efficiency of the Operation Weeting team casts further doubt on the conduct of the people who led the previous inquiries. Only the second part of the Leveson inquiry might get to the facts. No police officer, for example, has been questioned at trial about the original investigation.

In the end this is a story about power. And Murdoch just got too powerful. He owned too much of Britain's media estate. He still does. But it's politicians that gave Murdoch his power. And I'm sorry to say, I don't see much changing. They're still queuing up to take a bow, albeit less obsequiously than before.

Without rules that stop the monopolistic tendencies of the powerful people who run our media, can we, with any certainty, say that a similar situation will not arise again? I'm certainly going to campaign for a Labour manifesto commitment to widen pluralism in our media market.

And now that we have a verdict, I hope the party leaders ask themselves: do we tackle the problems relentlessly and ensure nothing like this ever happens again to vulnerable, powerless people?