Four animals rights activists were found guilty yesterday of blackmailing companies who supplied a controversial animal testing research laboratory.

Four animals rights activists were found guilty yesterday of blackmailing companies who supplied a controversial animal testing research laboratory.

Gerrah Selby, 20, Daniel Wadham, 21, Gavin Medd-Hall, 45, Heather Nicholson, 41, and Trevor Holmes, 51, were alleged to have orchestrated the campaign which ran against firms linked to Huntingdon Life Sciences in Cambridge between 2001 and 2007.

All five denied conspiracy to blackmail but Selby, Wadham, Medd-Hall and Nicholson were found guilty yesterday at Winchester Crown Court. Mr Holmes was cleared of the charge.

One of the jurors refused to be seen in court while the verdict was announced after 33 hours and 48 minutes of deliberation. Sentencing will take place on January 19.

Selby, Wadham and Medd-Hall were released on conditional bail, while Nicholson was remanded in custody. Three other people - Gregg Avery, Natasha Avery, and Daniel Amos - have pleaded guilty to conspiracy to blackmail.

The hierarchy of the group, called Stop Huntingdon Animal Cruelty (Shac), used threats such as claiming that managers of the firms were paedophiles, hoax bomb parcels, criminal damage, and threatening phone calls to force firms to cut links with the company.

The aim was to target suppliers or any company with a secondary link to Huntingdon Life Sciences (HLS).

One of the features of intimidation included sending used sanitary towels in the post, saying they were contaminated with the Aids virus, and personal campaigns against the management of companies, including daubing roads outside their homes with words such as "Puppy Killer".

Nicholson, from Hampshire, was a founder member of Shac, who managed the "menacing" campaigns against the firms who were named on the group's website.

The blackmail would stop only when they put out a "capitulation statement" to Shac saying they would not supply HLS, which conducts animal testing for the pharmaceutical industry, the court was told.

Medd-Hall, from south London, was a computer and research expert high up in Shac who uncovered company links with HLS. Wadham, from south-east London, joined Shac in 2005 and was in regular attendance at demonstrations against the firms and HLS.

Selby, from west London, was also a regular activist at demonstrations in the UK and Europe, including a violent demo in Paris. Mr Holmes, from Newcastle upon Tyne, was alleged to be a senior member of Shac who took part in criminal damage in the UK, the court heard.

Detective Chief Inspector Andy Robbins, senior investigating officer of Kent Police, said outside court: "This verdict reflects the continuing commitment of law enforcement and the Crown Prosecution Service to bring to justice those who seek to repress reasonable discussion and who commit serious offences in the name of animal rights.

"This conspiracy to blackmail involved the systematic and relentless intimidation of individuals and their companies whom Shac suspected of supplying Huntingdon Life Sciences. I would like to pay tribute to the many victims who had to carry out their lawful business while living through this criminal campaign."

Mr Robbins said Shac and the Animal Liberation Front (Alf) were "one and the same" and that cash donations were used to fund criminal activity. "There's no club and no rules of membership," he added. "The Alf is simply a name given to criminal behaviour."

An HLS spokesman said: "Freedom of expression and lawful protest are important rights in our democratic society but so too is the right to conduct vital biomedical research, or to support organisations that perform such research, without being harassed and threatened.

"The UK environment for such biomedical research has improved greatly in recent years. This is the direct result of positive action by agencies to control animal rights extremism. As a consequence we have seen greater openness in the research community that must lead to improved dialogue and better understanding - animal research remains a small but essential part of such research."

CPS reviewing lawyer Alastair Nisbet said: "The sole aim of Shac was to close down the business of Huntingdon Life Sciences in Cambridgeshire because they use animals in the testing of pharmaceutical products. That testing is required by UK and European legislation."

He added: "The victims were just carrying out their normal business but were nonetheless themselves described as criminals."