Apart from being a huge embarrassment to ministers, the Civil Service and the Commons Speaker, the decision not to prosecute Damian Green or the man who leaked to him has important implications for the running of government.

By deciding that Christopher Galley, the leaker, is not guilty of an offence the Crown Prosecution Service appears to have given a green light to members of the Civil Service to disclose without fear of prosecution, even though if caught their jobs could be in jeopardy.

The DPP concluded that the leaks – some of which were deeply embarrassing to the Government – was not secret information or information affecting national security and did not expose anyone to risk of injury or death. Moreover some of the information leaked touched on matters of legitimate public interest.

The civil servants involved have already been accused by the Home Affairs Select Committee of over-egging the pudding. But their claims that national security was involved were repeated by ministers including Jacqui Smith and may indeed have been inspired by them.

It is another gift for the Opposition in a week of Easter presents. Coming on top of the Damian McBride affair, it will be cited immediately as another sign of an authoritarian government whose time is up. It has still not been established as to what extent ministers were knowledgeable about these decisions and actions; and if they were not, why not?

Police operational independence does not absolve ministers from accountability or responsibility.

The ruling is a boost for freedom of the press but it will leave ministers and future ministers wondering if they will have to go about their business in a different way in future.

In the short term it will put pressure on Michael Martin, the Speaker, and his officials.

Mr Martin must now run the gauntlet of inquiries into the affair, amid demands for answers over why police were allowed to search the Tory frontbencher’s office without a warrant.

Several MPs broke convention last year by publicly suggesting Mr Martin should stand down, on the grounds that he could no longer be relied on to protect their rights.

The furore forced Mr Martin to take the unusual step of justifying his actions in a statement to the House. He insisted he had not personally authorised access to the parliamentary estate for the controversial raid that took place on November 27, while Mr Green was being arrested and questioned for nine hours.

Instead, Mr Martin laid the blame on Jill Pay, the Serjeant-at-Arms, who he said had “regrettably” granted permission without his explicit say-so. However, he also lashed out at Scotland Yard, claiming they had failed to “explain, as they are required to do, that the Serjeant was not obliged to consent or that a warrant could have been insisted upon”.

The allegation drew a sharp response from police, with the officer leading the probe, the then Assistant Commissioner Bob Quick, insisting Ms Pay had sought legal advice before providing two forms of written authorisation.

The Commons authorities have so far blocked the publication of any of the potentially embarrassing documentation - which could show what the Speaker and his officials knew, and when.

It is bad for the Speaker. But this week, of all weeks, it is another serious blow for ministers.

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