William Denison, managing director of F2 Chemicals, told how he and his family became a target of a six-month campaign because his company was linked to the animal testing laboratory Huntingdon Life Sciences.

Letters saying he was a paedophile were allegedly sent to 200 families in his village and a hoax bomb was sent to his home in 2003, he told Winchester Crown Court.

Mr Denison also told how letters were sent by the Animal Liberation Front (ALF) to his home several times a week.

The trouble peaked in summer 2003 when 14 messages, such as "Bill the murderer" and "Bill, the ALF are coming for you", were daubed in red paint on a 500m stretch of road near his Lancashire home.

The prosecution claims the actions were part of a campaign by Stop Huntingdon Animal Cruelty (SHAC), which targeted companies with links to Cambridge-based Huntingdon Life Sciences.

The hierarchy of SHAC is alleged to have conspired to blackmail such companies and the prosecution claim there is a direct link between them and illegal activity by extremists.

F2 Chemicals did not directly deal with Huntingdon Life Sciences, but supplied a Japanese glass company which had closer links.

Mr Denison told how the repeated attacks, which included fireworks being set off over the house and airhorns being sounded late at night, led to his wife leaving her job with stress.

Five people are on trial – Trevor Holmes, 51, Gerrah Selby, 20, Daniel Wadham, 21, Gavin Medd-Hall, 45, and Heather Nicholson, 41 – who are alleged to have tried to force companies to sever links with the animal testing company.

All five deny conspiracy to blackmail from 2001 until 2007.
Three other members – Gregg Avery, Natasha Avery and Daniel Amos – pleaded guilty to conspiracy to blackmail.

Proceeding