A disgruntled businessman launched a bizarre hate campaign against an innocent family who purchased a fish farm which he wanted to buy, a court heard today.

Robert Walker, 50, threw leaflets from a moving car stating that the children using the Oakbank Fisheries in Longtown, Cumbria were at risk from paedophiles employed at the complex.

He contaminated a fish-filled pond with oil and even sent proprietor Sidney, 46, and Margaret, 41, Boulter's 12-year-old son rat poison through the post.

The year-long campaign left the terrified owners fearing that the site would be bombed and when police raided Walker's County Durham farm a hoard of explosives were found.

Newcastle Crown Court heard how Walker had made a £190,000 bid for the leisure complex when owner Michael Powell died suddenly in 1998 and it was offered for sale.

Having made the offer he sought to drive down the price by claiming that the land was riddled with defects.

After months of haggling the vendors pulled out of the deal and refused to negotiate further.

Prosecutor Christopher Knox told the court: "Between July and September 1999 a position was reached whereby the price was reduced to £175,000.

"But by the same token the vendors became fed up with what they perceived as messing about and withdrew so far as this defendant was concerned.

"On September 22 1999 the vendors said they didn't want anything more to do with the proposed purchase."

The court heard that Walker's campaign started by him contacting the police, fire brigade, environmental agency, fisheries department, Carlisle council and environmental health to complain about defects at the property.

On October 26 1999 Ruth Walker, his common-law wife, was on the telephone for two hours to the fire bridgade querying the company's fire regulations and certificates.

By April 5 2000 the Boulter's offer of £150,000 was accepted and contracts were exchanged, making them the new owners.

But Mr Knox told the court: "Significantly the defendant was still making offers to purchase. He was still overtly trying to buy it despite the fact he knew the Boulters were involve.

"In December 1999 they had offered £120,000 and continued to make offers. On April 4 2000 he offered £140,000 and a few days later £160,000.

"The defendant was very keen to buy this property. He found out the sale had gone through on April 5 and that is why it starts turning really quite nasty.

"Walkers reaction was prompt. On April 7 the defdenant contacted the Carlisle police. He said he was a survivor of sexual abuse and was skilled at recogniseing abusers.

"He identified a man he called Brian who worked at the fisherie. He said he was a peodophoile and needed to be looked at.

"He said he had no direct evidence but insisted the police should look at this man becasue Brian took young boys fishing and it gave him an opportunity to abuse them."

Mr Knox adeded: "This kind of allegation clearly had consequences. The police had to investigate, even in the vague terms it was put.

"There was a person called Brian there but the police found not a shred of evidence of any inpropriety by this person. But the campaign, say the prosecution, had started."

The court heard that onm the morning of June 5 Mrs Boulter found a leaflet proped up on top of a full drum of diesel at the premises.

It read: "We, the people of Longtown, do not want your sort on the doorstep. Get out while you still...."

The court heard that Walker faxed a letter to the Boulter's solicitors the morning after the find, offering to buy the premises. That same day oil and diesel were poured into a lake where there were fish kept.

Mr Knox told the court that by June 15 the campaign "started in earnest". Derogatory leaflets were sent throught the post across Cumbria. They were stuck to lamposts and thrown out of a passing car.

Mr Knox added: "The prosection that this was the defendant. This is what he was up to, maybe with assistance from his wife, but this was the defendant at work." One of the leaflets read: "Save our school kids. Peadophiles are operating at Oakbank Fisheries. You know what to do! Encourage then to close down. Which City Councillor is involved iwth the site? Sod off sex offenders. Leave Longtown now."

The leaflet was signed "The Longtown Reivers" and mentioned a councillor who had nothing to do with the complex.

Another leaflet said: "Public safety warning. Peadophiles operating in this site. Don't risk stay. Clsoe them down now. Boulter back to Penrith.

Mr Knox told the court: "The intention was to frighten the Boulters into believing violence would be used opon them."

A copy of one of the leaflets was even sent eo the chief executive of Cumbria Council.

The leaflet campaign took a terrifying turn when SOS was painted on roads and signposts nearby and a mention of "explosive art for the pyrotechnician" was mentioned.

Mr Knox added: "Mrs Boulter, in so far as she was concerned, thought fireworks, fire, danger, violence."

On July 11 a packet of rat poison addressed to Danny Boulter was sent by post to the Boulter's teenage son. This was after he had appeared in a local newspaper for winning a fishing competition."

Mr Knox said: "In the context of this campaign it was clearly intened to indicate to the people who are part of this family that they are at risk of personal violence."

In July 18 Walker made another official bid to get the Boulters to sell the farm.

On September 4 police raided Walker's farm at Waterhouses, near Esh Winning, County Durham, and found a pipe bomb, four modified flash units, gunpowder, a length of copper pipe, a modified torch, milk cartons containing petrol, pyrotechnics, and a battery timer unit.

An alarm clock which was altered to act as a timing device was also found. Mr Knox 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.

He denies two charges of harassment and one of having an explosive substance.

The trial continues.