The activists were banned from HLS in June

Sarah Gisbourne, 39, was also given a two-year Anti-Social Behaviour Order to start on her release from prison.

Gisbourne was arrested in Hampshire, where she was living in November and later pleaded guilty to conspiracy to cause criminal damage.

She was sentenced at Peterborough Crown Court for offences from last July which caused �39,000 in property damage.

It was said in court that she attacked vehicles linked in some cases, though not all, with Huntingdon Life Sciences.

Clear message

Cars were attacked with paint stripper and tyres were slashed.

Assistant Chief Constable Anton Setchell, national co-ordinator for Domestic Extremism (NCDE), said after the hearing: "The sentence sends a clear message to other potential extremists that they will be caught and convicted.

"It will also provide reassurance to victims of animal rights extremism.

"The crimes committed by Sarah Gisbourne caused great distress to the victims and this result shows that offences of this type will not be tolerated.

"This conviction has resulted from co-ordinated police work between Cambridgeshire Constabulary, Surrey Police and Hampshire Constabulary. It was a detailed and protracted investigation.