A gang of G20 protesters launched a battle for compensation against Scotland Yard today after prosecutors dropped charges against them.
The tongue-in-cheek group drove a bright blue armoured vehicle into the City of London on April Fool's Day at the height of anti-capitalist demonstrations.
Eleven members of the gang, known as the Space Hijackers, were arrested when they jumped out wearing riot police-style helmets and blue overalls.
They were charged with impersonating police but the case was dropped after four hearings as their trial approached.
The Crown Prosecution Service (CPS) said new information led prosecutors to believe there was no longer a realistic prospect of conviction.
The Space Hijackers said they were looking forward to causing more chaos in the four days they had booked off work for the trial.
And they said solicitors would now sue the Metropolitan Police for compensation as they fight to get their vehicle and equipment back.
In a statement, they said the case was "one of the most bizarre prosecutions" in recent years and an "utter waste of taxpayers' money".
They added: "We always refuted these ridiculous claims on the part of the police and the Crown Prosecution Service and invited people to look over the past 10 years of our work, which the police were well aware of, to see that we have a long history of parody, dressing up and winding up the powers that be."
The protesters stopped outside Royal Bank of Scotland (RBS) offices in Bishopsgate at the height of demonstrations that marked the meeting of world leaders.
The six-wheeled vehicle, complete with gun turret, was emblazoned with a black and white chequered livery and the word "riot".
Officers escorted it to a weighbridge in Wapping where they checked if it was roadworthy before arresting all those inside on suspicion of impersonating police.
The vehicle, an Alvis Saracen of the kind once used by the British Army in Northern Ireland, is owned by the group and has previously appeared at arms fairs.
The group were some of 20 people charged with offences in the aftermath of two days of protests in the City.
An investigation was launched after a series of angry clashes, including a raid on another branch of RBS in Threadneedle Street, beside the Bank of England.
London Chief Crown Prosecutor Alison Saunders said: "In November 2009 we received information from the defence team acting for these individuals and as a result we asked the police to gather further evidence which we received this month.
"That evidence and further evidence provided by the defence team this month, included the fact that the individuals were part of a theatre group and that members of the public had thought it was a stunt.
"In order to prosecute an individual with impersonating a police officer the CPS must prove that that an individual did so with intent to deceive.
"Although we had evidence from a police officer that within the context of the G20 protest some members of the public did believe these individuals to be police officers, this further evidence indicates that others did not and that there was no intent to do so.
"The CPS keeps all ongoing prosecutions under continuous review and will discontinue any case if we believe there is no longer a realistic prospect of conviction."
Solicitor Raj Chada, of Hodge Jones and Allen, said: "We are delighted that the CPS have at last seen sense.
"This was always a ridiculous case and the CPS' time and effort could have been better spent looking at bringing prosecutions for potential police misconduct.
"Our clients are looking forward to the return of their tank and we will be considering what further action can be taken against the police."
Those facing trial were Londoners Jessica Barter, 19, of Newham; Leah Borromeo, 30, of Brockley; Mohammed Hayder, 25, and Suzan Keen, 41, of Hackney; Paul Hardcastle, 23, and Stephen Jewkes, 29, of east Dulwich; David Parkhouse, 23, of Homerton and Robin Priestley, 32, of Aldgate.
Others who faced trial were Stephen Gibbens, 21, of Milton Keynes; David Vannen, 38, of Abbots Langley, Hertfordshire and Rebecca Walpole, 21, of Seaforth Road, Aberdeen.Reuse content