The phone-hacking scandal linked to the house of Murdoch is starting to assume the quality of one of those fast-moving epic dramas in which, if you miss a single scene, you are in danger of losing the thread entirely. After the arrest yesterday of Rebekah Brooks, all bets were already off about what had been billed as tomorrow's spectacle, the appearance before the Culture, Media and Sport Select Committee of the two Murdochs, father and son, plus Ms Brooks. Some even suggested that the arrest had been timed to undercut public interest in the interrogation.

By nightfall such questions had been largely effaced by an entirely new twist, namely the sudden resignation of the head of the Metropolitan Police, Sir Paul Stephenson - an event that drew attention away from the scandal as a purely Murdoch affair, and back to the excessively close, one might say incestuous, relationship between News International and the Met.

It is important to note that Sir Paul has in no way admitted wrongdoing, or knowledge of News International paying the police for information. And when such claims first emerged, his initial response was robust. But in recent days, the support of senior politicians had ebbed away and sounded ever more conditional. As allegations continued to swirl around the Met about improper relationships with the Murdoch empire, doubts increased about whether he was the right person to continue playing a leading role in an investigation into the newspaper's affairs. His own credibility was undermined by the fact that he had hired Neil Wallis, a former deputy editor of News of the World, who was arrested last week in connection to phone-hacking charges, as PR chief for the Met at a time when the police faced calls to reopen inquiries into the newspaper.

With Sir Paul's departure, pressure will now grow on John Yates, the Assistant Commissioner of the Met, who decided against a fresh investigation into phone-hacking allegations in 2009.

In one sense, the charges of misconduct being laid at the door of the Metropolitan Police were always more significant than those imputed to the bosses of News International. Nefarious doings are almost part of the warp and woof of a certain kind of muck-raking journalism, whose lifeblood is the exposure of the secrets of the rich.

These newspapers certainly need to be held to account when their hot pursuit of secrets leads them across a red line into acts of flagrant illegality. However, we should not exaggerate the degree to which the misdeeds of a clique of journalists and editors affect the life of the country as a whole. For all the talk of media empires whose tentacles allegedly stretch into every corner of the British Establishment, it is worth remembering that not everyone in this country reads Murdoch newspapers, or is remotely touched by what they do or say. It is a quite different matter with the police. An honest and uncorrupted police force is a vital pillar of society without which no healthy democracy can maintain itself. If a corrupt culture has indeed embraced parts of an organisation in which we have placed such enormous trust, that should worry everyone.