Early in his first term as Prime Minister Tony Blair said education “standards were more important than structure”. But five years on ministers seem as keen on changing school structures as their Tory predecessors.

In a speech last term about tackling problems faced by London’s schools, the Education Secretary said she wanted to see more specialist schools and city academies in the capital, and proposed schools for five to 16-year-olds. She also floated the idea of breaking up large secondaries into smaller schools.

Ms Morris cited the example of Boston, Massachusetts, which has successfully trialled small schools and now plans to break up 12 high schools into 200-350 pupil units.

“For them it has worked,” she said. “It’s given stability, continuity and made the notion of the school more manageable in terms of the social relations and the stability that students need.”

The movement to reorganise large schools into smaller units, often on same site, has a growing following in the United States. Supported by some of the country’s biggest charities, it received a boost two years ago when a federal programme was launched that in its first year helped 349 schools divide into smaller “learning communities”.

US studies show that young people, especially from deprived backgrounds, benefit from attending smaller, less impersonal schools. Such schools are said to have better attendance and lower levels of violence and disruptive behaviour, though their impact on student achievement is less clear.

On this side of the Atlantic, where large secondaries may not be as impersonal as their US counterparts, the argument for “downsizing” seems less compelling. According to Kate Griffin, incoming president of the Secondary Heads Association, successful large schools will create a caring environment despite their size.

Referring to her own 1,500-pupil school, Greenford high in Ealing, west London, she said: “I run my school on a house system and heads of house know their children extremely well ... so the small units work well within the larger unit.”

Ms Griffin also pointed to the apparent contradiction between the Government’s drive to encourage schools to join forces under one successful head, and its new-found enthusiasm for small schools.

With headteacher vacancies already difficult to fill, she questioned whether there were enough suitable people to take up the new posts that would be created by dividing up large schools.

Malcolm Noble, head of Bexleyheath school, which with 2,100 pupils is the largest in London, did not dismiss the micro-school idea out of hand. But he said: “The great advantage that we have as a very large school is that we get huge economies of scale both in terms of costs and also in the range of courses we can offer.”

Bexleyheath creates a “human-scale” environment by ensuring pupils meet tutors every day, and by managing its lower, middle and upper schools separately.

Not surprisingly, heads of smaller schools seem more in favour of the idea of breaking up large comprehensives. “I think it’s more difficult to gain consistency across a really huge institution, and to make sure youngsters feel they really belong,” said Linda Austin, head of Swanlea school in Tower Hamlets, which has 1,050 pupils. “Having said that, clearly there have been some very successful large schools.”

The Department for Education and Skills has not yet decided whether to break up some of the capital’s larger schools. A spokeswoman said: “London faces unique problems. We are floating a number of radical ideas and we want a debate. Micro-schools are one option and there are many more.”