They have been behind one of the most successful recent public mobilisation campaigns.

Since Peter Roberts of the Association of British Drivers (ABD) posted a petition to scrap the Government’s road-pricing policy on the No 10 website, it has amassed more than 1.5 million signatures. But those behind the group, which claims to be the “voice of the driver”, are rather quiet about explaining their other operations.

One is a scientist who insists on using a pseudonym and believes that global warming is a sham. Another doesn’t own a car and runs a PR firm whose clients include a number of public environmental bodies.

The association is against speed cameras and the current speed limits and calls global warming “the biggest con trick ever perpetrated on the human race”. Run under the incorporated name of Pro-Motor, it has five directors. It was founded in 1993 by Brian Gregory and claims to have 2,000 members.

Mr Gregory, 52, who by day is a sales and marketing executive in a pigment manufacturing firm, said that he had founded the organisation in the wake of the Road Traffic Act 1991, which paved the way for speed cameras.

He told The Times that his organisation struggled to find funding because “our views are seen as radical and not along the lines of the perceived wisdom of the moment”.

“We’ve approached many of the car manufacturers and they say they agree with a lot of what we’re saying but they don’t want to put their corporate heads above the parapet.

“It’s not that they don’t agree with us; they’re frightened what radical elements in the so-called road safety movement will do in terms of chaining themselves to car showrooms.”

He said that the group’s environmental spokesman, Bernard Abrams, insisted on being quoted under a pseudonym. “The only problem for Bernard is that because he operates as an environmental consultancy he’s been threatened with business being taken away from him because of his views on climate change. His customers believe it could affect their business adversely. He will probably want to be quoted not under his own name for that reason.”

Mr Abrams, 49, who goes by the name of Ben Adams, rejects the notion that humans are causing rises in the Earth’s temperature, and says it is cooling.

An ABD director, Fellow of the Royal Astronomical Society and former Ofsted inspector, he runs his own consultancy group, Education Management Associates, in Cheltenham.

Yesterday he refused to take phone calls, and said in an e-mail: “Somebody in my position joining the ABD does so for specific reasons and one of mine was the misunderstandings being promulgated over the environmental impact of car use.

“I value my family’s privacy and my right to unassailed family life extremely highly.”

A third director is Mark McArthur-Christie, 40, the group’s policy director. He told The Times that he didn’t own a car, preferring a motorbike and bicycle combination.

His day job is as a director of Freeman Christie, a communications and PR company based in Witney, Oxfordshire.

The firm’s website lists the Environment Agency as a client, and its environmental policy is to “ensure that transport choices are, wherever possible, sustainable” and encourage “alternatives to the car”.

Mr McArthur-Christie said he was in the ABD to change it, and that he saw absolutely no contradiction between Freeman Christie’s operations and those of the ABD, which calls for vast roadbuilding programmes and cuts in fuel duty.

The group’s treasurer, Hugh Bladon, 65, a former major in the Royal Army Pay Corps, said that he believed all speed limits should be scrapped but feared that “we don’t have enough people with sufficient intelligence to be able to drive accordingly”.

Paul Hemingway, 44, the fifth director of the firm, works as a marketing manager for Land Rover at its headquarters in Gaydon, Warwickshire.

When The Times called him at work he claimed to have no knowledge of Land Rover. When it was pointed out to him that Land Rover’s switchboard had connected the call, he said he was “not going to be a director of ABD for much longer”.

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