New laws which form the bedrock of government plans to bolster workers' rights face a backlash from American-style "union busters".
Campaigners wishing to take advantage of a landmark change in the law, which grants unions obligatory recognition under certain circumstances, could find their best-laid plans being pulled apart by the "busters".
At least one US firm of consultants admits to having been in contact with UK companies about the changes in the law.
The company, PTI Labor Research, feels there is so much interest from UK bosses who fear a return to 1970s-style trade union militancy, it plans to set up a London office later this year.
Now British unions say that some home-grown legal firms are following suit.
Recently, new laws which form a core of the Employment Relations Act, were enacted. These grant unions automatic recognition in the workplace if more than 50% of workers in a "bargaining unit", for example a factory, are union members.
If membership is lower, a union can gain recognition where 40% of the overall workforce vote yes in a ballot.
A first for unions
It is the first time compulsory union recognition has been enshrined in British law.
Similar rules are long established in the United States and, over the years, have led to the practice known as union busting.
Martin Jay Levitt, who wrote the 1993 book Confessions of a Union Buster, estimated 10,000 lawyers and consultants were involved in the $1bn per year anti-union campaign industry.
A common tactic of the "busters" is to round up staff and show them videos that attack trade union practices and portray negative case histories.
Mr Levitt, who spent nearly 20 years as a "labour relations consultant", says one common tactic was to grill supervisors about what workers were thinking, and drill them in the use of anti-union propaganda.
Bill Ragen, an organiser with AFL-CIO, the American equivalent of the TUC, says while most "union busters" stay within the law they abuse the worker-boss relationship.
"The employer has total access and a powerful relationship. You put a bunch of people in a room, make them sit down and shut up and generally increase the tension in the workplace and people feel so pressured they will vote no just to get it over with," he says.
It is an analysis that Carolyn Jones, of the London-based Institute of Employment Rights, agrees with.
"They are basically creating an anti-union condition. All staff will gather in one room and the employer will put on a video which contains a negative case history."
The problem is that unions often cannot put up an effective defence. They lack the funds and the ability to organise during company time, on company premises.
Texas-based PTI Labor Research has more than 1,000 companies on its books in the US, many with UK operations. The company's Stuart Keene, says it has received an amazing response from those fearing the new union-friendly laws in Britain.
Intimidation
Mr Keene rejects the intimidation charges levelled at the industry and dismisses Mr Levitt's claims, calling him an outsider.
"If we have clients who are not up-front and legitimate people, we do not get involved," he told BBC News Online.
The company sells its own information videos, which have titles such as "Unions: Just say NO!" and which, says Mr Keene, are based entirely on fact. These will be available to UK clients when the company sets up in London.
Texas-based PTI has advised Britain's largest firm of employment lawyers, Eversheds, in the run-up to the new Act. Recently Eversheds hosted a UK seminar to which firms such as McDonald's and The Gap were invited.
Eversheds partner Martin Warren stresses the firm acts for all sides in employment law, and will do so in union recognition cases. So far there has been little interest among management opposed to union recognition but that is set to change with the new Act, he says.
Defensive action
Mr Warren says there is no plan to form an alliance when PTI moves to the UK, "but inevitably we are going to be asked by some employers to defend against unions".
Like PTI, Eversheds will use videos to put the case to employees, but Mr Warren rejects the idea of anti-union propaganda.
"We would refuse to act on pressure. We take an ethical stand and our principles are to act within the law and within the ethics we have.
"I'm talking about a balanced, impartial, non-partisan approach. We would have a message to put across, but it will be done in a level-headed and logical manner."
So far the Trades Union Congress is unconcerned about "union busting".
'Scare-mongering'
Sarah Veale, senior employment relations officer at the TUC, says there has been some scare-mongering by consultants looking to capitalise on the new regulations in the UK.
"We expected this. It's not very nice. It's opportunism. If a company has so many employees who they think will vote for recognition they ought to be thinking differently about it," she says.
There is also a fear the practice could tip the largely peaceful balance that currently exists between many unions and employers.
With American outfits eyeing up a potentially lucrative and largely untapped market in the UK, others may follow in the footsteps of PTI and set up over here.
It, by the way, is working flat out to open its London office in the first week of September, when Americans will be enjoying their annual workers' holiday - Labor Day.