A Kent-based gangmaster couple have agreed to a landmark settlement worth more than £1m in compensation and legal costs for a group of migrants who were trafficked to work on farms producing eggs for high street brands.

The deal reached with six Lithuanian chicken catchers is the first settlement of a claim against a British company in relation to modern slavery, and came after the group became frustrated at the lack of a criminal prosecution.

Ten other claimants are now expected to bring similar cases against DJ Houghton Chicken Catching Services, of which Darrell Houghton and his wife, Jacqueline Judge, are the sole directors.

The couple agreed to the compensation deal after a high court ruling this year found that they had failed to pay the national minimum wage, had made unlawful deductions from wages and had failed to provide adequate facilities to wash, rest, eat and drink.

The claimants alleged to the court that they had been threatened and assaulted by Lithuanian supervisors who intimidated them with fighting dogs, and that they were housed in appalling conditions.

They said they were forced to work back-to-back eight-hour shifts for days at a time and were denied sleep and toilet breaks, forcing them to urinate in bottles and defecate in carrier bags in minibuses as they travelled between jobs on poultry farms around the UK.

A Guardian investigation in 2012 revealed that one of the businesses that regularly used the Houghton company for casual labour was Noble Foods, the leading producer of eggs to supermarkets and owner of the Happy Eggs brand.

The legal case has raised questions about the extent of Noble’s information about the conditions endured by the Lithuanian workers it was using.

In his defence filing, obtained after a Freedom of Information request, Darrell Houghton said Noble had required him to install a GPS tracking system in his minivans so that it could monitor where the chicken-catching gang were at any time. Noble has admitted in correspondence that it received tracking data but told the Guardian it was not aware of the workers’ conditions.

Noble Foods is the UK’s largest egg company and both the firm and its former chairman, Peter Dean, have been major donors to the Conservative party. The company helicopter was on occasion loaned to David Cameron for election campaigning. The company has recently been restructured and is under new management.

Noble Foods said: “The welfare and treatment of all employees of Noble Foods, or those working for the company via a third party, is of paramount importance. The condition under which certain contracted staff employed by DJ Houghton Catching Services had been working in 2012 was not known to Noble Foods and resulted in the immediate and permanent cessation of DJ Houghton Catching Services’ contract.”

The Lithuanians were sent to work in supply chains producing premium free range eggs for McDonald’s, Tesco, Asda, M&S and the Sainsbury’s Woodland brand. The farm sheds they cleared of chickens also produced eggs sold under the Freedom Food brand.

The migrant workers were trafficked to the UK from Lithuania by a man whom the Houghtons admitted paying to find workers for their chicken catching business. As poultry production has become more intensive and large-scale in recent decades, the job of catching the egg birds when they have come to the end of their laying life has been outsourced to specialist travelling teams of catchers. Houghtons was one of a tiny pool of agencies offering the service to UK producers.

The plight of their Lithuanian workers was uncovered when some of the men turned to a Citizens Advice Bureau for help. In 2012 Kent police, the Gangmaster Licensing Authority and what was then the Serious Organised Crime Agency conducted joint raids on houses owned by the Houghtons to liberate more than 30 men believed to be victims of human trafficking for labour exploitation.

The supermarket companies said at the time that they were shocked by the allegations and would take action to ensure their ethical standards were met fully.

Laurynas Kelpsa, one of the Lithuanian workers who brought the claim for compensation, said he was happy that a civil settlement had finally been reached after four years, although he remained disappointed that the police had not brought charges.

“It has been a really hard time for me, not just physically but mentally, and for all of us victims. I am really excited that we have got justice at last,” he said. He plans to use his share of the compensation award to set up his own car valeting business.

The legal action was led for the Lithuanians by solicitors Leigh Day on a mixed basis of no-win, no-fee and legal aid. Shanta Martin, a Leigh Day partner, said the award should act as a deterrent to others who planned to exploit migrant workers.

“We are extremely pleased to have achieved this result for our clients as it will go a huge way towards helping them rebuild their lives. The large bill faced by the defendants is also a salutary lesson to other who might seek to profit from modern slavery,” Martin said.

Noble Foods said it had instigated “a major review of its existing systems to ensure strict protocols were in place to protect all employees and enable any wrongdoing to be identified at the earliest opportunity”.

Houghtons did not respond to requests for comment. The Guardian understands that it has settled the claims relating to threats and assault without admitting liability.