A man has told a court he was accused of being a paedophile by animal rights activists because of his company's links to an animal testing laboratory.
Vincent Howard of Biocair in Cambridge also said he was sent a hoax bomb.
Five defendants, from Hampshire, London and Newcastle, allegedly blackmailed firms connected to Huntingdon Life Sciences (HLS) in Cambridge.
The five, said to have been part of Stop Huntingdon Animal Cruelty (SHAC), all deny conspiracy to blackmail.
Heather Nicholson, 41, of Eversley, Hampshire; Trevor Holmes, 51, of Newcastle; Gerrah Selby, 20, of Chiswick, London; Daniel Wadham, 21, of Bromley, south London and Gavin Medd-Hall, 45, of Croydon, south London, are accused of being closely involved in a campaign, from 2001 until 2007, which targeted companies in Britain and Europe.
Three other people, Gregg Avery and Natasha Avery, both of Hampshire, and Daniel Amos, of no fixed address, pleaded guilty to conspiracy to blackmail, Winchester Crown Court court was told.
Biocair and its employees were targeted in 2004, jurors were told on Wednesday.
SHAC, which was based at near Hook, Hampshire, demonstrated outside the company's offices as part of a worldwide campaign to target suppliers or any company with a secondary link with HLS, jurors heard.
Biocair, a distribution company, did not deal directly with HLS but it did work for firms that had links with it.
Giving evidence, operations director Mr Howard said in September 2004 his and his partner's cars had paint stripper poured over them and tyres punctured.
He said letters were later circulated in the village where he lived in Cambridgeshire falsely accusing him of being a convicted paedophile.
"There were 25 to 30 sent around the village, if not more, and it became fairly well known in the village and people offered to pass them on (to the police) without opening them up for forensics," he explained.
When asked how it had affected him, Mr Howard replied: "I was very lucky. I work long hours and I didn't have that many connections with the village.
"Whereas my partner was well connected with the schools and well known in the village, which helped a lot because she was able to contact the schools and say these letters were completely bogus."
The couple also received a hoax bomb through the post in April 2006, the jury heard.
"My partner was suspicious because there were inaccuracies on the address label," he explained.
"I probably unwisely asked her to lift up a bit and look inside. She saw a DVD case with wires inside and I started to come home straight away."
The trial continues.