It was as difficult to walk through parts of Manchester earlier this month without bumping into a lobbyist as it has been for Liam Fox to visit a foreign capital without meeting up with Adam Werritty. Literally thousands of lobbyists took the trip north for a week's social networking and deal clinching at the Conservative Party conference. There were more of them there than Tory representatives. Their presence went a long way to covering the cost of an expensive week that would otherwise have had to come from Conservative Party funds.

"It's difficult to distinguish between the Conservative Party and the lobbying industry, because the revolving door between the two is so well-oiled," Tamasin Cave, who runs the Alliance for Lobbying Transparency, said.

This phenomenon has grown since the election. Before then, whatever the lobbyists' private opinions, power was with the Labour Party and it was around Labour ministers that lobbyists hovered, while David Cameron vouchsafed he would curb their activities once he was in power. Now it is Tories who draw the lobbyists, and Labour that is calling for regulation.

No one is suggesting that it would be possible, or even desirable, to ban lobbying altogether. Businesses are affected by the decisions politicians make and are entitled to call on the services of experts to help them make sure that ministers understand what they are doing.

Where this £2bn-a-year industry becomes a target of suspicion, and a potential source of corruption, is when its practitioners operate in secret, either by pretending that they are motivated by beliefs when in fact there is money involved, or by trying to disguise the fact that they are lobbyists.

Common sense suggest that deceit like this should be illegal, but it is not. Although an uncounted number of politicians have talked about subjecting the industry to regulation, it has not happened. This is not because there has been resistance from the industry. Helen Johnson, who heads the Association of Professional Political Consultants, says that her organisation is in favour of legislation.

From time to time, new rules have come into place when a scandal has blown up around rogue lobbyists, but too often, somebody finds a way around them.

The most effective way to prevent "in-betweeners" from bending the rules would be to force them, by law, to come out from any dark corners where they may be hiding, say who they are and who is paying them to do what. It should not be difficult to get legislation through Parliament. All it needs is the political will. If the Government suddenly finds the will, we can thank Adam Werritty.