Johal Dairies orchestrated the theft of a rival's confidential invoicing data and used it to poach customers with the offer of free milk, a court judge has ruled.

In a High Court case last week that sheds light on the fiercely competitive middle-ground milk market, Johal Dairies Ltd was found to have paid illegal immigrant Gurbir Singh £40,000 to steal invoices from JN Dairies Ltd containing volumes, addresses and prices for all its customers.

Johal denied the claims but several JN Dairies customers testified they had been approached by Johal directors "and seen copies of their previous invoices or given information that could only have come from such invoices".

In a damning judgment, Judge David Cooke declared the evidence of Surbjit and Gurnek Johal "highly unconvincing" and said the invoice theft was a "pre-arranged plan" organised by Surbjit Johal. A hearing in July will determine what sanctions Johal will face.

Experts said Johal's court costs could reach £1m but the damage to its reputation could be far greater. One customer of JN Dairies was offered free milk for four weeks and another for three months. One retailer contacted by The Grocer, who had been supplied by Johal for 20 years, said he was paying around 90p for two litres, while a customer of JN Daires was recently offered a rate of 70p by Johal.

In a statement Johal said it was "extremely surprised and disappointed" by the ruling and would be asking the Court of Appeal to overturn the findings.

"In seeking to appeal, Johal Dairies maintains its denial of any wrongdoing," its solicitors said. "Johal... is confident it will continue to enjoy the loyal support of its customers and suppliers and will continue with business as usual."

JN Dairies founder Jaspal Singh Nijjar said: "We do not have a problem with fair competition and have been successfully competing with Johal and other companies for years but unlawful activity to attack our business will not be tolerated by JN Dairies. Nor will the law allow anyone to get away with it."

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