Seeing the video of Ian Tomlinson being assaulted by a police officer during the G20 protests – an apparently innocent man being subjected to what appeared to be an unjustified assault by a police officer – provoked in me an immediate desire for the perpetrator to be suspended, tried and punished.

On the other hand, having been the victim of "trial by media" myself, I realised the need for an independent investigation, the outcome of which is not pre-judged. Similar conflicting feelings arose over the demise of Assistant Commissioner Bob Quick.

Putting a significant anti-terrorist operation, if not the lives of police officers and members of the public, at risk, by displaying a summary of the operation to the world's media, was a serious security breach. When the terrorists involved in the Madrid train bombings realised the police were coming, they blew themselves up, killing one and injuring many other anti-terrorist agents in the process. The same could have happened here. Conversely, you can put yourself in Mr Quick's position, on his way to brief the Prime Minister and Home Secretary at No 10 about a major operation, reminding himself of the key points on his journey to Downing Street and without thinking, failing to cover-up his secret brief before he got out of the car. It was a sad way to go over such a simple but potentially serious mistake.

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What, if anything, do these incidents tell us about the state of British policing? The most obvious link is public confidence in the police service. The uniquely British concept of policing by consent, where the police rely on the active participation of the public relies on us having trust and confidence in our police officers. The police have a unique range of powers including the use of force and the power to arrest and detain (for up to 28 days in the case of those arrested on suspicion of terrorism this week) on the grounds of suspicion alone. We entrust these powers to the police on the basis of having confidence in police leaders, believing officers will use their powers appropriately and in the knowledge that if the powers are misused, that those responsible will be held to account.

In terms of public trust and accountability, the case of Ian Tomlinson did not start well. Scotland Yard issued a statement the day after his tragic death claiming that he had no contact with police officers before they tried to resuscitate him. Whilst the circumstances were very different, the parallel with misleading statements made by the police in the immediate aftermath of the shooting of the innocent Brazilian at Stockwell have not gone unnoticed.

We do not know what the exact circumstances were in the Tomlinson case, what provocation the police officer may have been subjected to immediately prior to the video clip or what Tomlinson might have said or done before he is caught on camera. Police officers are often put into very testing and sometimes dangerous situations when trying to control demonstrations and whilst we expect them to be highly trained and professional, they are also human. Conversely, we expect a higher level of tolerance and self-control from police officers than from the public, making the apparent behaviour of the police officer in the video footage far more serious than the antics of the demonstrators.

Sir Paul Stephenson is learning quickly and the hard way that it is not easy being the Commissioner of the Metropolitan Police. Acting decisively in suspending the officer involved will help to endorse his "no-nonsense" reputation but such action, and his comments that the Tomlinson video raises "obvious concerns", will have some rank-and-file officers asking whose side the Commissioner is on.

Sir Paul has just replaced Sir Ian Blair as Commissioner – a man many rank and file officers did not believe was "a copper's copper", someone who understood what it is like for them out on the streets.

Sir Paul Stephenson is also running out of experienced officers at a senior level. Since joining the Metropolitan Police as its Deputy Commissioner four years ago, he has lost two heads of counter-terrorism, Andy Hayman and Bob Quick, and the Commissioner, Sir Ian Blair, all of whom were forced to resign, and Assistant Commissioner Tarique Ghaffur who agreed to go in a negotiated settlement following allegations of racism. Despite Quick's involvement in the Damien Green affair and the Conservative Mayor of London announcing Quick's departure, I am not convinced that those forced out have been the victims of partisan politics.

Being well regarded by his colleagues and strongly recommended by the previous Commissioner, John Stephens, allowed Mr Quick to take charge as Chief Constable of Surrey relatively early in his career, returning to the Met a few years later as an Assistant Commissioner. The Tories may have been eagerly awaiting Quick's next mistake but I believe Hayman, Blair and Quick have all been the authors of their own demise. Of greater significance is that, at a time when the senior team in the Met has been significantly weakened, it is strong leadership that the Metropolitan Police desperately needs.

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Recent events could justifiably give rise to concerns that we have a police service whose leaders do not appear to have a grip of their own responsibilities, let alone control over the actions of their subordinates. At the same time, the Tomlinson case and those of Jean Charles de Menezes and Mark Saunders, raise the spectre that the bad old days of British policing may be returning, of "canteen culture", the use of excessive force and of a police service that appears to be unaccountable – the officer concerned in the case of Mr Tomlinson apparently being allowed to cover his face and numerals.

Sir Ian Blair tried to continue the liberalising work started by Sir Peter, now Lord Imbert, when he was Commissioner. These police reformers were swimming against the tide of the prevailing culture, trying to produce a more inclusive police service that is more responsive to the needs of the public, and more representative both in terms of gender balance and minority ethnic representation. Sir Ian Blair failed to reform the Met and the temptation for Sir Paul Stephenson is to go with the flow of the dominant male macho culture, but at the cost of failing to tame the minority of canteen cowboys who do so much damage to the reputation of the police service.

Changing organisational culture requires difficult decisions. My concern is not that the current Commissioner is not capable of such bravery, but that he does not have the strength in depth in his team, or the will, to carry through what are very necessary police reforms. He will need strong political backing if he is to succeed.

On the beat: Views from the blogs

*PC Blogson, planetpolice.org

I had no idea how secret and top secret documents are handled. Now I know. Plonker. Assistant Commissioner Bob Quick didn't just show a secret document to the press, he showed one so sensitive that an anti-terror operation had to be brought forwards [sic], one can only assume, thereby jeopardising months of work and meaning there may not yet be evidence to prosecute the suspects.

*Posted on 200weeks.police999.com

Bob Quick is an Assistant Met Commissioner in charge of counter-terrorism. He's also a bit of a numpty.

*areatracenosearch.blogspot.com (a response team working in the south of England)

In my carrier we ran a competition for spotting the best bit of graffiti. The only rule was that the graffiti had to be on a police vehicle. Our favourite was one of the armoured warthogs with "PIGS" sprayed tastefully below the police sign on the bonnet. Spot on.

Scary moment when I got hit by something, and looked at my arm to notice that I was bleeding heavily through my boiler suit. I realised it was just a tomato the protesters had thrown.

I think that actually our tactics were sound, and most if not all of us did a bloody good job. I also think that the majority of genuine protesters were at the very most only an annoyance, and frequently friendly, intelligent and often entertaining.

The small minority determined to use force and attack everyone that stood in their way were shameful. They were the reason that the genuine protesters were held back and shepherded about, they were the reason that negative press was given, they were the reason for injuries on both sides, and they were yet another nail in the coffin for legitimate, lawful, peaceful protest.

*pcbloggs.blogspot.com

As the PC who turns up to your door when you have been burgled/robbed/ texted by a ne'er-do-well, I can tell you that the prospects of my snaring a serial rapist by anything other than blind luck are precisely zero.

As if in some kind of landmark policy, Met Commissioner Paul Stephenson has ruled that his officers should walk the beat alone from now on.

This will apparently make them more approachable, oh and double the number of patrols. Which conveniently means that he can get away with employing half the number of officers.