AN embittered businessman who carried out a bizarre campaign of intimidation against a couple who bought a fish farm that he wanted has been jailed for five-and-a-half years.

Robert Walker, 50, of New Ivesley Farm, Esh Winning, carried out a vicious vendetta against Sidney and Margaret Boulter of Longton, in Cumbria. He claimed paedophile activity on their farm, contaminated a fish-filled pond with oil and sent rat poison to the Boulters' 12-year-old son through the post.

During a three-week trial at Newcastle Crown Court last month, the jury was told that when police raided Walker's farm, they found a pipe bomb, four modified flash units, gunpowder, a modified torch, milk cartons containing petrol and an alarm clock altered to act as a timing device.

Walker, an Oxford graduate who studied trade-unionism, had said the campaign was nothing to do with him but was found guilty. He was convicted of two charges of harassment and one of having an explosive substance.

Christopher Knox, prosecuting, said some of the explosive equipment was usually found in a 'terrorist context' and were 'crude but effective' weapons.

Walker, who holds a shot gun certificate and fire arms licence, was arrested and told police he knew nothing of the pipe bomb.

He claimed that the pyrotechnics were to put on displays for his wife and everything else had a legitimate purpose.

But Judge Tim Hewitt said on Tuesday: "All were capable of being used together as a crude incendiary device. The crown cannot say what their intended use was but it is clear if either were used as part of this campaign those devices, crude as they were, were capable of causing significant damage, injury or both, quite apart from the terror caused to those against who they might have been used."

Judge Hewitt also ordered that Walker pay £13,694 prosecution costs.

Judge Hewitt said he was satisfied that the Boulters were terrified and traumatised by the campaign.

He added: "You have been convicted on overwhelming evidence of conducting a nasty, vicious and frightening campaign of intimidation. Your target was an innocent family who had successfully purchased a country property with which you had become in my judgement obsessed."

After the case Det Sgt Peter Proud, of Carlisle police, described Walker as a 'devious and clever' man.

After the case Mr Boulter said the case had put a huge strain on his family and he is considering making a civil claim against Walker