The most appealing aspect of an often bizarre Conservative election platform was the proposal to make it far easier for new schools to enter the state-funded sector. Under Tory proposals, anyone who passes regulatory muster can set up a school and bid to attract pupils, who will come neatly packaged with state funding. The Conservatives want to expand dramatically the range of choices, introducing new, innovative schools and perhaps reinvigorating older schools with the bracing winds of competition. But will it work?

The Conservatives point to Sweden and to the US, both of which have introduced policies along these lines. In their manifesto they wrote that in Sweden, “standards have risen across the board as every school does its best to satisfy parents”. The evidence is more ambiguous than that. Early studies of the Swedish reforms looked impressive; more recent work has raised some questions.

In the US, the evidence is more encouraging, but – warns Joshua Angrist of the Massachusetts Institute of Technology – it comes with a health warning. British reformers sometimes talk casually about the benefits of American “charter schools” as though this was some well-defined category. But different US states have very different regimes. Some have simply liberalised entry without much regulatory oversight. Others, such as Massachusetts, are stricter and close down charter schools that are failing to deliver.