Roger Graef: Police dressed up as Robocop act like him too

A few days of protest in the City of London six months ago may soon affect the management of dissent in our democracy. The final report from Her Majesty's Inspector of Constabulary, due shortly, will address the tactics used at G20 which some observers feel are inconsistent with policing by consent. Are they right?

Dispatches filmed the Metropolitan Police training officers to manage demonstrations, and saw safety training given to all recruits. It found that aggressive moves used at G20 were not exclusive to rogue officers out of control, but were in the Acpo manual. The reason officers are dressed like Robocop – and sometimes act like it – is based on a legacy of violent protest.

G20 was one of the biggest police operations in years. Hastily convened to respond to the financial meltdown it gave police three months to plan instead of four years. Forty thousand people arrived to protest about everything from bankers to climate change. That diversity meant there were no leaders with whom to negotiate. Confusion reigned about who could speak for – and to – the various groups.

Protest varied from peaceful sit-ins blocking the main City road, to a number of marches – staged without obligatory police permission – and a hard core, which police put at 1,500, determined to damage property. Containing their behaviour while allowing non-violent protest was a key driver of police strategy.

The Met's supply of trained manpower was stretched to the limit. Despite some violence and damage to a branch of the RBS, the limited cost contrasted with the chaos and millions worth of destruction in 1999 when protestors went on the rampage. The G20 operation was deemed by the Met to be a success. But days later, images of Ian Tomlinson struck from behind appeared on the net, followed by others of police hitting protestors with open hands, batons, and shields. The outrage prompted investigations by two select committees, and the HMIC review.

The Met was accused of having overreacted and using inappropriate tactics such as "kettling", keeping thousands contained for hours because of troublemakers in their midst. Police defended the operation on the grounds of protecting property, office workers and residents. They also pointed to the illegal marches and protests they permitted, such as the seven-hour Climate Camp protest allowed to block the A10 before being "robustly" cleared.

The fearsome riot uniform has literally changed the face of policing. Former Met Commissioner John Stevens and Chris Fox, previous head of Acpo, are among those who worry that it provokes the very trouble it was meant to prevent. Our film shows how the strategy and kit evolved from the serious violence of the 1980s, when many officers were injured and PC Keith Blakelock was killed at Broadwater Farm. Today senior officers risk being sued if officers are injured on duty.

The overwhelming number of demos and marches in London pass off without incident. Yet the Met feel its two days of training must prepare officers for the worst and polls suggest the majority support tough police action. But peaceful dissent is vital to democracy. After G20, senior officers want a debate to help them strike the difficult balance between non-violent but unlawful protest by a minority and the rights of others to go about their business. Our film offers important new evidence to help the public judge how it wants to be policed.

Roger Graef is executive producer of Dispatches: Ready for a Riot, shown tomorrow at 8pm on Channel 4