In Ms. Truss, they found a friend. After a youthful dalliance with the Liberal Democrats, the new prime minister’s belief in small-state libertarian politics has been a mainstay of her political career. In 2011, just a year after entering Parliament, she created the “Free Enterprise Group” of backbench Conservative lawmakers “to renew the case for genuine free markets and free enterprise.” As environment secretary, she embraced austerity, insisting that funding cuts for her department were “a big opportunity.”

Appointed head of international trade, Ms. Truss seized the chance to staff her operation with libertarians. In October 2020, just a couple of months before the start of Britain’s new life outside the European Union, Ms. Truss appointed several pro-Brexit, free-market figures to advisory bodies in her department. Among them were Mark Littlewood, the head of the Institute for Economic Affairs; Matt Kilcoyne, at that time the deputy director of the Adam Smith Institute; and Robert Colville, who runs the Center for Policy Studies. Daniel Hannan, a key architect of Brexit, had been appointed as a trade adviser a month earlier. His think tank, the Initiative for Free Trade, was formerly based at 57 Tufton Street.

This battalion of free-market thinkers has now been welcomed into 10 Downing Street. Five of the new prime minister’s closest advisers are Tufton Street alumni, including Ms. Truss’s chief economic adviser and her political secretary, and at least nine Tufton Street alumni are scattered across other major government departments. Tellingly, Mr. Littlewood says that Ms. Truss has spoken at his think tank’s events more than “any other politician over the past 12 years.”

The political imprint made by these groups, whose stalls have proudly lined the Conservative Party’s annual conference this week, may be relatively easy to track. But the way in which they operate is not so clear. Notoriously opaque about their sources of funding, something they defend as a right to privacy for donors, they have been found by investigative reporters to have financial links to the oil giants BP and Exxon Mobil, big tobacco companies and American libertarian groups. But the picture depicted is only partial. We simply do not know who is bankrolling the groups now at the heart of the British government.

That’s a problem, for the power they exert on British democracy — arguably now at its zenith under Ms. Truss — is considerable. First and foremost, they are significant operatives in Conservative circles: The Center for Policy Studies, for example, claims that it was “responsible for developing the bulk of the policy agenda that became known as Thatcherism.” Given that Margaret Thatcher herself co-founded the think tank, it’s not an idle boast. In the decades since, groups like it have multiplied as the Tufton Street network evolved from a pseudo-academic forum to an orchestrated lobbying outfit whose influence stretches well beyond the Conservative Party.