The Chief Constable of the West Midlands police works from the seventh floor of a high-rise work-scuffed office block in the centre of Birmingham, a city caught in the spasms of rapid and confusing reconstruction.

Those same words describeequally accurately the process taking place in his detective branch.

This week Chief Constable Geoffrey Dear, in a 12-hour purge of surgical swiftness, cleared out more than 50 detectives including the operational head of the CID and other very senior officers.

Another police force has already begun investigating the alleged criminal activities over a three-year period of members of the serious crime squad. Monday of this week in Birmingham was not so much a night of the long knives as a day of some very short conversations.

In those few hours Dear did what no other chief constable has done before. First, he acted; then he set up an official inquiry; and finally he went public, explaining what he had done. Hitherto those same steps have had a very different sequence.

In a mere half-day of concentrated action he broke a 150-year-old mould and he will not be readily excused by more sober traditionalists.

Already, critics are saying he acted prejudicially, behaved rashly and -more seriously - lacked loyalty to long-serving and dedicated policemen who are not even suspected of wrong doing.

Within the police service, at all levels there had been no room this week for hedged bets. In his handling of the affair so far you either believe he is a brave man or a foolish one.

But Geoffrey Dear is untroubled by the swirling controversy. In a headquarters isolated by roadworks and marooned among diversions that lead nowhere, it would be easy for me to draw ananalogy of a force under siege but to do that would be inaccurate.

Yesterday the building was busy with media crews asking questions about his investigation into the Hillsborough disaster, but amid the turmoil I sensed a feeling of relief among ordinary policemen that the unhappy decision had been made. There was understanding for the suspended detectives but little sympathy.

The Chief Constable unequivocally argues that his ruthless action was for the eventual good of all the force and he seemed confident that the morale of his men and women will suffer no lasting damage.

I wondered whether he truly understands the hurt and humiliation of the police officers concerned, most of whom he accepts may be personally blameless. Yes, he does, and is quite unrepentant.

In matters of corruption he says, it is a perilous exercise to draw the line too low. "It is," he told me "sometimes necessary to take out an entire command structure."

I asked him about that awful word "corruption" with its unavoidable connotations of dark corners, brown envelopes and policemen on the take, because in the current cases there is no suggestion that West Midlands policemen have been involved in such activities.

Indeed, it is the opposite; the allegations are that some Birmingham detectives bent the rules and broke the law to put suspected villains behind bars, not that they took money to look the other way.

I asked him whether, in the murky world of violent crime and compromised morality, he could ever accept that otherwise honest cops sometimes do unlawful things to suspected criminals not for personal gain but out of a misguided sense of public duty?

He paused and then confessed to a split second of surprise at the ready use in newspapers of the word corruption to describe shoddy and lying police work but nonetheless he was firm.

"There can be no distinctions. That argument neither condones nor mitigates what they do." In his book, corruption is a broader issue than a fistful of folded tenners.

Yet, despite some Press reports he is not implacably opposed to elite squads such as the now disbanded and discredited serious crimes squad. But he is exceedingly cautious about them.

"They are often very desirable but if you set up a squad - especially one with an aura - leadership must be of the highest quality. The difference between results you want - achieved properly - and things going badly wrong is only a whisker away."

At which point the discussion moved to matters of Scotland Yard where he was an Assistant Commissioner. Did his actions this week reflect any London lessons he had learned? Were there any comparisons with Sir Robert Marks?

He said: "You can draw a parallel, although the gist of the problem is different. Mark was an incredibly brave man who took on a corrupt organisation. He adopted a public position and I also have taken a public stance."

But he made it plain he has no fears of endemic corruption within the West Midlands force.

Dear's powerful and unprecedented announcements about the specifics of this case have already debarred him from eventually sitting in disciplinary judgement on any of his men - if it comes to that - but he says his responsibility as a chief constable over-ruled any niceties of established procedure.

"It is a chief's job to be up there with the decisions; he is paid to do it."

He believes passionately in responsible leadership and acknowledges he has staked his personal reputation on an eventual outcome which may or may not support his drastic actions. He is braced for the possible flak.

Geoffrey Dear is one of the country's most talented senior police officers and is quietly tipped as a future commissioner of the Metropolitan Police.

His enemies are already saying that his actions this week are an early bid to establish his credentials for that top job. That he turned a provincial problem into burgeoning crisis merely to demonstrate that he can cope with it.

I went to his beleaguered Birmingham office prepared to test that theory. I came away convinced that personal ambition had no role to play in the dramatic events of the last few days.

Geoffrey Dear did what he did simply because it was the right thing to do and in doing it, set a new benchmark for the future handling of cases such as this.

It has been a sad and painful week for the West Midlands police, especially those tarred with the broad and sometimes unfair brush of corruption. But, in the long run, I believe that they, and Geoffrey Dear, will be the stronger for it.