A Littlehampton animal rights activist known as ‘Mumsy’ has been jailed for six years for a shocking campaign of intimidation against an animal testing lab.

Sarah Whitehead, 53, of Thorncroft Road, led an attempt to close down Huntingdon Life Sciences by intimidating companies linked to it.

Winchester Crown Court head today how she and five others waged a wide-ranging international conspiracy of intimidation against a host of supply companies to force the closure of Cambridge-based HLS.

They used a group, Stop Huntingdon Animal Cruelty (Shac) as a front for their illegal activities.

Action carried out included realistic hoax bombs posted to the homes of staff and offices, criminal damage, threats of violence and abusive telephone calls.

Some company directors had leaflets distributed near their home falsely telling neighbours they were convicted paedophiles and others had used tampons sent through the post saying the blood was HIV positive.

Others had words like puppy killer, murderer and scum daubed on their houses, cars or on the roads nearby.

The abuse would only stop when the company issued a capitulation statement on the Shac website and cut links with the lab.

The total cost of damage and increased security costs was £12.6 million, to around 40 companies targeted, the court heard.

Jailing Whitehead, who was called "Mumsy" by the others, for six years, Judge Keith Cutler said she led the younger members on and corrupted them.

He said she had carried out up to five direct attacks a night on one occasion and she was "a long-term campaigner and trusted insider" within the conspiracy who had not shown remorse and would be likely to offend again.

Nicole Vosper, 22, Thomas Harris, 27, Jason Mullan, 32, and Nicola Tapping, 29, were also jailed at a hearing today.

The youngest member of the conspiracy Alfie Fitzpatrick, 21, received a 12-month prison sentence suspended for two years and was ordered to complete 100 hours of community work.

The six were part of a larger conspiracy involving the founder members of Shac, Gregg and Natasha Avery and Heather Nicholson, who used the organisation as a front to intimidate companies under badges like the Animal Liberation Front or the Animal Rights Militia.

Whitehead, Vosper, of Bay View Terrace, Newquay, Cornwall, and Harris, of Somerville Road, Ringwood, Hampshire, admitted conspiracy to blackmail companies and suppliers linked to the Cambridge-based company between 2001 and 2008.

Mullan, of Holloway Road, London, Tapping, of Somerville Road, Ringwood and Fitzpatrick, of Knowle Road, Solihull, West Midlands, all pleaded guilty to conspiracy to harm Huntingdon Life Sciences from 2005 to 2008 under the Serious Organised Crime and Police Act 2005 by interfering with companies supplying them.

The maximum jail term for conspiracy to blackmail is 14 years and for conspiracy under the Serious Organised Crime and Police Act 2005 it is five years.

Other members of Shac, including the founder members Gregg Avery, Natasha Avery and Nicholson, were jailed in January 2009 at Winchester Crown Court for blackmailing companies linked to HLS.

Sentencing, the Recorder of Winchester, Judge Keith Cutler, said the well-planned and relentless campaign had been "synonymous with intimidation, violence and terror".

"The action was taken in order to distress and terrify, and in that you were successful," he told them.

He said that the lawful activities of Shac were a "thin veneer" and it was a vehicle for intimidation even though he accepted the six had a passionate opposition to animal research laboratories and had "fiercely held beliefs".

He then quoted Mr Justice Butterfield, who jailed other members of the conspiracy, when he said: "I expect you will be seen by some as martyrs for a noble cause but that would be wholly misplaced.

"You are not going to prison for expressing your beliefs, you are going to prison because you have committed a serious criminal offence."

Vosper was also described as a trusted insider by the judge and jailed for three and a half years. She took part in direct action against targets, but was described as having intelligence and ability.

Mullan's role was described as not insignificant and he had been part of Shac since 2002. The judge said he viewed with horror Mullan's behaviour while on a demonstration in Paris in April 2007 and jailed him for three years.

Harris was described a taking over the running of Shac after others were arrested in 2007 and he was fully aware of what others were doing. He was jailed for four years.

Tapping, the judge said, was not on the front line and did not carry out direct action, but she knew what was going on. She received a 15-month jail term.

Fitzpatrick was only 17 when he was part of the conspiracy. He was educated at the international school in Geneva and is from a wealthy family. The judge said he was the least involved and received the suspended sentence.

Whitehead also received a 10-year Anti-Social Behaviour Order banning her from taking part in animal rights activities with the others receiving five-year ASBOs on the same terms.

Police said that since the arrests in 2007, animals rights extremism had been dramatically reduced.

The cost of the operation was put at £4 million.

Detective Chief Inspector Andy Robbins from Kent Police, who led the operation, said: "The sentences passed today are a fitting reflection of the systematic and relentless intimidation of individuals and their employers, carried out by a small group of criminals.

"Such tactics have no place in a democratic society and in no way reflect the peaceful protests carried out by the vast majority of legitimate animal welfare campaigners."