A former high-flying Kings of Wessex School pupil has been jailed for conspiring against firms linked to Europe's largest animal research centre.

Nicole Vosper, 22, originally of Cheddar, was sentenced to three-and-a-half years in jail at Winchester Crown Court on Monday for conspiracy to blackmail.

She has already served 19 months in custody after pleading guilty in March last year. Upon her release she will be subject to a five-year anti-social behaviour order.

She was arrested with five other members of protest group Stop Huntingdon Animal Cruelty in May 2007 during a £4.2 million investigation into animal rights extremism.

The particulars of the charge against Vosper and two others saw them try to stop companies they suspected of trading with Cambridgeshire-based Huntingdon Life Sciences through blackmail, menaces and intent to cause loss between 2001 and 2008.

Alastair Nisbett, of the Crown Prosecution Service, said: "These defendants were not legitimate animal welfare protesters but people who were prepared to carry out criminal acts, which tormented and deeply distressed their victims, sometimes over a number of years.

"They threatened and intimidated those who were going about their lawful business because they personally objected to the victims supplying goods and services to Huntingdon Life Sciences.

"Those who have not been subject to such a campaign cannot understand how harrowing it is to be constantly on your guard against threatening letters and emails, vandalism to your home and car and even hoax bomb threats. Or what it's like to have your neighbours and employers told, maliciously and repeatedly, that you are a paedophile."

Vosper, of Bay View Terrace, Newquay, was a conscientious pupil at Fairlands Middle School and Kings in Cheddar.

She wrote powerful letters on animal testing for the Cheddar Valley Gazette's letters page between 2002 and 2004 and was a founder of Fairlands' Animal Rights Group in 2001 at the age of 13.

She was part of a winning debate team on vivisection the year before and went on to join Kings' Amnesty International group.

At the age of 15 she wanted to take part in a nude protest against the running of the bulls in Pamplona, Spain but was told to wear underwear and hold a placard instead for legal reasons by People for the Ethical Treatment of Animals.