The leafy, picturesque surroundings of Broughton Hall - surely the only business park where black Labradors roam the car park - seem a million miles away from a cold, dark night in Morecambe Bay.

From her office, Janet Wilkinson has a fantastic view of the Craven countryside in which lies the historic estate, now transformed into a thriving centre for commerce.

Vernon Wheelock Associates, the relatively small consultancy firm set-up by a former Bradford University academic in 1990, has for a long time been a key advisor to businesses on a range of issues surrounding food safety.

But since last year's arrival of Miss Wilkinson - former head of the technical centre at CWS - it has become a leading force in the field of ethical trading and, with that, the increasingly concerning issue of gang masters.

The incident in Morecambe Bay, in which at least 20 Chinese cockle pickers perished after being caught by a rising tide while getting just £1 a day for their efforts, has catapulted the issue into the public consciousness.

For Miss Wilkinson it was a tragedy that had been waiting to happen and won't be the last.

But she is also confident it will make more suppliers to some of Britain's biggest retailers take increased interest in the type of labour being used in their own supply chains.

The use of gang masters has been long-established in rural areas of the UK for various agricultural practices such as picking and packing.

Miss Wilkinson, however, says the practice is spreading because of the nature of today's economy, with the big retailers demanding fresh produce 24 hours a day.

The need to respond speedily to supermarkets' demands for more goods on their shelves often forces suppliers to call upon big groups of casual workers to fulfil an order quickly.

"The pattern of employment has changed," she said. "The consumer wants and expects fresh produce seven days a week and that puts pressure on the packers to get the products. That is why the retailers are being blamed, even though many of them are the ones who are really pushing for standards to be improved."

The issue has created a growing demand for the services offered by the eight-strong team at Broughton Hall, which can call upon a vast array of associates around the country.

It goes into firms - often major food manufacturers supplying own-brand products to the leading supermarkets - and audits them according to the principles of the Ethical Trading Initiative (ETI) base code. Miss Wilkinson was at the forefront of the development of the ETI which was introduced by former Government minister Claire Short in 1997.

The ETI, run by a board comprising Government, the corporate sector, trade unions and non-governmental organisations, was a response to revelations surrounding the use of child labour in manufacturing overseas.

The problem emerged in the early nineties when it was revealed children were being used to stitch footballs. It soon became apparent that these youngsters were also being exploited in terms of pornography, prostitution and drug trafficking.

Miss Wilkinson, who at the time worked for the Co-op, one of the founder members of the ETI, was in charge of ensuring the organisation could confirm its supply chains complied with the code, which covered a range of basic workers' rights.

However, it became increasingly apparent that the problems were not just overseas. And the situation at home now concerns Miss Wilkinson most in her new role in Skipton.

While the Morecambe incident was an extreme example, she said many of the workers employed by the gang masters in the UK were being exploited. Many don't receive the national minimum wage, don't get sick or holiday pay and may have deductions illegally taken from their wage for accommodation or protective clothing.

Many of the workers will also be encouraged to continue to claim benefit to make up for the low wages.

"It is very difficult to get to who is running these gangs because the workers are often absolutely frightened to death," said Miss Wilkinson. "They won't want to tell because of the fear factor.

"In Morecambe, they still feared the police even when they were flying in their helicopters overhead trying to rescue them. They are living in appalling conditions and getting paid very little."

Mrs Wilkinson said it was hard to estimate the numbers involved in the UK. The gangs are also prevalent in the construction industry, particularly in inner cities.

Many workers are illegal immigrants who are often led to believe they have official clearance because they have received papers from the gang masters.

One official report has estimated the figure at 70,000 workers, but Mrs Wilkinson said the real figure was likely to be much higher. But she stressed that not all the gang masters were operating illegally. "Some of them are doing all they can to operate within the law and it is a shame they are being dragged through the mud because of this," she said.

Now, in her role at Verner Wheelock, Mrs Wilkinson is hoping to uncover those firms which are wittingly or unwittingly supporting the trade.

"We are finding problems with agencies which haven't carried out audits and casual workers who aren't getting everything they are entitled to," she said.

"We haven't found anything yet where there is an immediate risk to life and limb but we have identified some major issues.

"It is a pity that that we have had to have a tragedy to do it, but the incident in Morecambe has focused people's attention on this issue and they have got a better understanding than they had before.

"Until then, a lot of people thought that these problems just existed overseas."