The Metropolitan Police in crisis

New chief faces concerns over bungled operations / Only two of top six posts filled on a permanent basis / Hundreds of experienced officers will quit this year

A succession of bungled investigations, a lack of leadership and the prospect of some of its most experienced officers facing compulsory retirement in the next year has plunged Britain's biggest police force into one of its most turbulent periods in recent history.

Already under pressure after the death of the G20 protester Ian Tomlinson and the botched investigations into two of the UK's most prolific sex offenders, the Metropolitan Police's list of problems increased yesterday with the revelation that only two of the six most senior positions at Scotland Yard are currently filled.

The leadership crisis was exacerbated by the unexpected departure of Bob Quick, who resigned this week after inadvertently leaking details of a top-secret terror investigation. It means that the force's upper echelons are severely depleted.

Only the Met Commissioner Sir Paul Stephenson, appointed two months ago, and Assistant Commissioner John Yates, appointed two days ago to succeed Mr Quick as head of counter-terrorism, have permanent positions. The other four most senior roles, the Deputy Commissioner and the three other assistant commissioners, are temporarily filled by acting officers who do not have the appropriate rank for the position they hold.

Added to that are the criticisms being made of the way the G20 demonstrations were policed. Mr Tomlinson died of a heart attack minutes after he was struck by a riot officer. Yesterday it was revealed that the Met has been forced to review its crowd control tactic, a cordon known as the "kettle", that was used to pen in 5,000 people last week. Senior officers will also be asked about whether the language they used when they spoke of violence ahead of the event contributed to the disorder.

The Met is also the subject of two separate Independent Police Complaints Commission investigations after officers' incompetence allowed John Worboys and Kirk Reid, two rapists, to stay free. Before that an Asian officer revealed that he was taking legal action after alleging that there was an apartheid system and rampant racism at Belgravia police station.

Most recently, the instability of the senior management team at the Yard has caused consternation. Pete Smyth, the chair of the Metropolitan Police Federation, said: "They do have a problem and they really need to sort it out pretty quickly. There are only two people sitting at the top table with the appropriate rank. The rest are acting up.

"There is nothing to say that the people that hold acting positions are not good enough to eventually be appointed to the post permanently, but we want that to happen soon. Police officers like stability and we haven't got that. We haven't had it for a long time. It seems to be one thing after the other and we just want stability."

There is another crisis on the horizon. The number of officers retiring has steadily increased from fewer than 500 in 2003-04 to nearly 800 in 2006-07. Last year's figures bucked the trend, with 598 officers taking retirement, but sources at the Met say they expect that number to rise in the coming years due to the legacy of a report published 30 years ago.

The Edmund-Davies report, from 1978, dealt with the problem of dwindling officer numbers in forces nationwide by recommending better pay. When the report was implemented in 1979 it brought about a pay rise of up to 45 per cent and saw officer numbers in the Metropolitan Police swell from approximately 21,000 to about 26,000. But, with police officers required to retire after 30 years, the Met faces losing some of its most experienced officers within the next few years.

Currently around 1,000 of the Met's 32,000 officers are eligible to retire and while recruiting new officers will not be a problem during a recession, those coming into the force will not have the experience of those retiring. With major events such as the Olympics looming, senior officers admit it is a problem.

Deputy Chief Constable Alf Hitchcock, of the National Police Improvement Agency, said: "Over the next few years forces, including the Met, are certainly going to see a lot more officers leaving. The Met is aware that this will be happening at the same time as the Olympics approaches – when they will need their most experienced officers.

"It is an issue and it is being looked at. We know that recruitment is not the issue here, most forces aren't short of people wanting to join them, it is experience," he added.

The management team's shake-up started in November 2008 when Tarique Ghaffur, the Assistant Commissioner of central operations, in charge of policing the Olympics, stepped down after settling a race discrimination case out of court. Chris Allison, a Deputy Assistant Commissioner in charge of public order, took on the title of temporary Assistant Commissioner and remains in that role. Then on 1 December last year Sir Ian Blair left his post after being told he no longer had the backing of Boris Johnson, the Mayor of London.

His departure meant that the then deputy, now Commissioner, Sir Paul Stephenson became acting Commissioner while Tim Godwin, the Assistant Commissioner in charge of territorial policing, became acting Deputy Commissioner. To fill Mr Godwin's shoes, Deputy Assistant Commissioner Rose Fitzpatrick became acting Assistant Commissioner and remains there.

Then this week Bob Quick, the Assistant Commissioner in charge of specialist operations, resigned. That vacancy was filled immediately, and permanently, by John Yates, the Assistant Commissioner of the specialist crime directorate. Deputy Assistant Commissioner Janet Williams took on Mr Yates's previous role on a temporary basis on Thursday.