Out comes the national security card

The Guardian says that the police claim that national security issues led to the arrest of Damian Green overshadows the release of a tory film of the search of his office. It could not have been more blatant that the security card was being played had they said "trumped" instead of overshadowed.

The first three lines of the Guardian article say it all:

The Metropolitan police conducted a search of Damian Green's parliamentary office last week after being told by the Cabinet Office that a series of leaks to the shadow minister could have posed a threat to national security.

Minutes after the Tories intensified the pressure on the police last night by releasing a short video showing the "rigorous" search, the Met hit back by highlighting the seriousness of the operation.

Sources said their investigation was prompted by a request from the Cabinet Office, whose officials told the police that the "systematic series of leaks" from the private office of the home secretary were so serious that they could pose a threat to national security. Police sources said this explained their decision to take the step - unprecedented in recent history - of arresting Green and searching his parliamentary office.

The police sources certainly know how to get their version of events in the paper without direct attribution or comeback.

When you dig into the national security claim, as subsequently set out in a letter from Jacqui Smith, it's fairly clear there is nothing in it:

She wrote: "Given the sensitive issues that the Home Office deals with - including matters of national security - there was a clear duty to take action to prevent leaks from happening."