For decades now, rightwing thinktanks have demonstrated an impact far beyond Westminster. They have been allowed to sow doubt into areas of settled scholarship, undermine academic expertise and camouflage outlandish free-market ideas. By incubating first Thatcherism and then Britain’s decision to leave the EU, they can lay claim to have helped decisively recast British politics twice in half a century. They have been able to do so because, instead of being engaged in scholarly research into social problems, they are the artillery in a long war of ideas. Such organisations, which rank among the most opaque over their funding, often act as business lobbyists.

It is clear that thinktanks that favour rightwing solutions, rather than leftwing ones, is where the dark money goes. In fact, so much has been documented on the subject that it is hard to see them as anything other than fronts for vested interests, concealed under a veneer of mock-academia and a questionable charitable status. The latest corroboration of such a thesis can be found in today’s Observer. It has an important story outlining why a network of pro-market thinktanks conceded liability for the “extreme public vilification” of a whistleblower who revealed unlawful overspending in the Brexit referendum campaign. They would rather admit these things than be forced to say who funds them in court.

The state has endorsed this behaviour in two main ways: one by failing to challenge thinktanks that say they are charities to show they are truly non-partisan. The second is to let them hide their funders – unlike the majority of UK research institutions. This has to stop. Under the law, anybody can set up a thinktank and pump in cash to produce studies to influence public perceptions. Just as Britain is getting ready to negotiate Brexit terms, foreign donors spent £1m, it is reported, to influence policy under the Adam Smith Institute brand. The best way of assessing whether they are corporate shills or not is to force thinktanks to show where their money comes from. Then they can participate in public debate effectively. In a democracy, it is only by bringing secrets into the light of the day that they can be examined.

Brexit has changed the atmosphere of political debate in profoundly damaging ways. Significantly for the newly aggressive leave vanguard, represented by a clutch of thinktanks, it has legitimised their dangerous heresy and redefined the previous orthodoxy as being biased and an out-of-touch remain, liberal worldview. The Brexit vote suggests Britain needs a more pluralistic intellectual climate. But this does not mean that partisan voices would create “balance” based on dubious research and deceiving the public about important issues in which their backers had financial interests. There is a good argument for the BBC to stop reporting on “studies” produced by, or promoting experts associated with, thinktanks that fail to voluntarily disclose their funding in detail on their websites. The shadow chancellor, John McDonnell, is quite right to say that in the interests of “openness and accountability” the BBC must distinguish lobbyists from thinktanks.

Thinktanks may argue that they advocate certain policies not because they benefit their funders, but because they are the right policy choice for the country. That’s fine – so they should list their donors. Thinktanks have no electoral mandate. Nor are they mass membership organisations. The legitimacy of their voice in democratic debates rests largely on their intellectual independence. They ought to demonstrate this by revealing who funds them.