Our report on the willingness of some all-party groups to accept findings from special interests which may push their causes is, from an institutional point of view, appalling in a proper democracy. It raises a series of questions. First, what on earth are the MPs thinking? It is probable that they are not. For some, the groups may offer contracts of convenience. The thought of an all-expenses paid jaunt to France or a fact-finding trip to Cyprus may be sufficient to win their views.

Most MPs, it is hoped, have not had their heads turned by avarice. Alternative explanations, though, are no less depressing. The dynamics of some all-party groups and their recent growth in numbers suggest that too many MPs are either too idle or careless of their reputations to worry about the precise wording of their report.

Secondly, who should police the groups? The system of minimal regulation to which they adhere has mutated. It is unfortunate, therefore, that Sir Philip Mawer, the Parliamentary Commissioner on Standards, has declined to intervene. This is the commissioner’s rightful territory. Sir Philip should reconsider.

Thirdly, what changes should be made? Several, and they all relate to transparency. To those politically committed souls already aware that an all-party group is a different creature from a select committee, the groups were regarded as essentially benign. We now know better. The access to Parliament that some groups have stealthily provided may be more far-reaching than the access bought through cash-for-questions in the mid-1990s. Toxic though that episode was for the reputation of Parliament, its impact was legislatively harmless. All-party groups, though, have given special interests a cloak of parliamentary respectability and a mouthpiece that wins them a hearing — and perhaps a profitable decision — in Whitehall departments. Some all-party groups are breaking the current rules by hiding the source of their financial, technical and secretarial support — trade associations and industry pressure groups. Those rules must be firmed up; there must be absolute clarity. Companies have every right to lobby on behalf of their interests, but the public has every right to know that they are doing so.

Anyone aware of the stranglehold that American lobbyists hold over Capitol Hill may be tempted to chortle at what could be dismissed by comparison as Westminster’s little local difficulties. In the US, lobbyists advise lawmakers politically, raise their money and work for their re-election, all the while persuading them of the merits of their corporate clients’ cases. We have no equivalent of Jack Abramoff, the lobbyist lifting the lid on all-party corruption in Washington. But the liberties being taken in Westminster could be a sign of worse to come.

There is nothing wrong with private companies or interest groups wanting their voices heard, or employing lobbyists to help them. But the dirty little secret exposed today is the emergence of a culture of complacency, collusion and, possibly, worse. Politicians must clean house, and now.