It was the free market at its most basic.

Ultimate Source was set up in 2000 with John Carter as director

Ukrainian Ruslan Kulish spotted a niche in the market and exploited it to the full.

He realised the demand for cheap, often seasonal, labour could not keep up with demand from farms and factories all over the UK.

Kulish was able to find plenty of young people from eastern Europe willing to work in the UK for relatively low wages but he needed to find employers.

There is a market for legitimate gangmasters...but we are trying to get those people who treat people absymally and avoid paying taxes in contravention of the system. Jim Sheridan MP Gang convicted of migrant racket

So he set up a bogus company, Ultimate Source, and found an English accountant and a sales manager who could help him find work.

They forged work permits and failed to pay hundreds of thousands of pounds in income tax and national insurance contributions.

The scam worked perfectly for three years until a bank became suspicious of cash being transferred and called in the authorities.

House of cards

In April 2003 police moved in and the house of cards which was Ultimate Source collapsed.

On Monday Kulish, his two English partners, and three people from the former Soviet Union, were convicted of crimes stemming from an investigation by Cambridgeshire police and the Immigration Service.

The firm provided fake work permits using a fake Home Office stamp

All six will be sentenced in April.

Ultimate Source was set up in 2000 with Carter as director and Mutch as the company secretary. Kulish appointed as field manager.

Carter set up the company and oversaw the operation and Mutch contacted farms and food processing factories in East Anglia and as far away as Cornwall and Inverness, in Scotland.

Ruslan Kulish used his contacts in eastern Europe to find the workforce and, being fluent in Russian and Ukrainian, he was able to liaise between the employers and workers.

Ultimate Source worked out of the trio's homes.

Russian language adverts

Many hundreds were recruited through adverts in Russian language newspapers.

Mutch was Ultimate Source's sales manager

The people behind Ultimate Source paid reasonable wages - up to �175 a week - and the employees were fairly happy with their lot.

They lived in caravans and were ferried by minibus to and from work.

Many saved their wages and went home to set up businesses with the cash.

The gangmasters meanwhile made profits of around �4m over three years.

But they were supplying their employees with false work permits using a fake Home Office stamp.

The farms and factories thought they were employing legitimate workers.

Several farmers had told the court they had been assured income tax and national insurance contributions would be paid by Ultimate Source.

Money stashed away

The profits, having been laundered in Britain and abroad, were invested in property and put in financial institutions.

Kulish owned four houses bought with cash. One cost almost �300,000.

Detectives found �121,000 in cash hidden in a box behind a bath panel in Kulish's bathroom.

Now Cambridgeshire Police will attempt to claim the properties and return the money to the Inland Revenue.

Further investigations are planned in an attempt to trace what happened to the rest of the money.

Ruslan Kulish and his girlfriend will be sentenced next month

Labour MP Jim Sheridan, supported by the Transport and General Workers' Union, is pushing through a private member's bill aimed at forcing gangmasters to become licensed.

The bill has been given its second reading in the Commons and the government has given it crucial support.

Mr Sheridan said the new bill would mean gangmasters could only operate with a licence and would have to ensure workers were properly paid, housed, insured, covered by work permits and that all taxes and national insurance contributions were covered.

Mr Sheridan said the bill would make farmers and factory bosses liable to prosecution if they used unlicensed gangmasters.

There would also be hefty fines and prison sentences for those who worked without licences.

Lyashkov and his girlfriend Viktoriya Kulish laundered money for the gang

He told BBC News Online: "There is a market for legitimate gangmasters and they are supporting my bill, as are the National Farmers' Union and the major supermarkets.

"We are trying to get those people who treat people absymally and avoid paying taxes in contravention of the system."

He said: "There are an estimated 3,000 gangmasters in Britain controlling up to 100,000 workers in agriculture alone.

"Many of these workers do not have the proper paperwork but are brought in to undercut the wages of ordinary farm labourers."