BORIS JOHNSON, London’s mayor, is keen to join the club of global city leaders who have transformed their schools. He wants to instigate a “gold club” for London schools that shine in rigorous subjects (the mayor is naturally attracted to Olympic imagery). A “London curriculum” would ensure no child will leave the classroom without knowing about Bow bells or the true story of Dick Whittington, a 14th-century merchant and lord mayor who (myth says) started off as an urchin with a cat. He wants to add more schools outside local-authority control. Some expect a leap forward for the coalition’s education reforms. Others fear a city hall power grab.

The capital’s state schools are no longer outright failures, as they were in the 1980s when the Inner London Education Authority was a byword for union strife and chaotically-run classrooms. On some measures they now outperform schools in other parts of the country. Pupils in both inner and suburban London obtain a higher pass rate in the five core subjects (which must include English and maths) in the GCSE exams sat by pupils at 16 than the national average (see chart). The stubborn performance gap between richer and poorer pupils has also narrowed in the city in the past decade. New academies (state schools run outside local authority control) have created beacons of achievement for others to learn from. Successful chains like the Ark academies started out in London. The Teach First movement, which launched in the city ten years ago, is now a national scheme attracting top graduates into the profession. A separate London Challenge project, which began under Labour in 2003 to improve the worst schools, has paid off handsomely, getting good teachers and experts to help tackle poor schools and track their progress more effectively. Yet the capital still has too few soaring successes. State education still frustrates parents and causes dinner-party angst. A third of parents in London fail to get their offspring into their first choice of secondary school. Private-school attendance in inner London is double the national average. Some local authorities are vying to regain control over those academies that are not faring well. Tony Sewell, a London education campaigner who oversaw the mayor’s inquiry report, criticises “unevenness” in the system. He points to discrepancies between boroughs and even nearby schools with similar demographics. Yet London’s distinct circumstances mean that it can make changes quickly. A projected 90,000 new school places will be needed over the next four years to cope with rapid population growth. That creates an opportunity to build lots more academies and free schools. London now has 27 free schools—like academies, but created from scratch—all of which have opened since the coalition took power in 2010. Mr Johnson wants to open a lot more.

Strictly speaking, this is mayoral overreach. Mr Johnson has barely any educational powers at all. But he does have access to land owned by city hall, and can indulge in discreet arm-twisting with the boroughs to persuade them to provide more space for new academies or free schools in return for municipal favours.

Lord Adonis, the former Labour minister who created the academies programme, believes that another layer of officialdom centred on the mayor’s court will “spawn more average bureaucrats than good schools”. Mr Johnson’s mission also perturbs reformist Tories close to Michael Gove, the education secretary. A bullish mayor running schools might well clash with Mr Gove’s national fief at the Department for Education, farther up the Thames at Westminster.

Much of this is political jostling. A push for excellence in the capital is unlikely to do harm—as long as the mayor can resist adding to the sprawl of officialdom or leaving a hostage to fortune when he moves on. It would be tragic if Mr Johnson’s legacy were to be a schools bureaucracy ripe for takeover by those keen to return to more dirigiste ways. As the Latin-loving mayor might put it: Caveat innovator.