After years as a byword for all that was wrong with education, London schools are improving fast. Last year, 51 per cent of secondary pupils got five or more good GCSEs, passing the national average, and three London boroughs were among the 10 fastest-improving education authorities in the country.

One of them was the once-notorious Islington - the place where Tony Blair couldn’t bear to send his children to school - where results leapt by more than 7 per cent to 46 per cent. Dysfunctional education authorities are functional again, and the capital has more teachers, less truancy and a more optimistic feel than it has had for a long time.

But how easy will it be to build on these improvements now that the immediate slack in what was a very slack system has been taken up? “It’s always easy to go up from a low base,” says Bill Clark, a director of CEA@Islington, the private firm running Islington’s school services. “We know we have to focus on a culture of relentless improvement.”

Relentless, because the odds remain stacked against the city and because London parents’ confidence in their local secondaries fell last year, according to a government poll. The capital’s pupils are the most deprived and transitory in the country. Three times as many have free meals, and five times as many do not have English as their first language. Many are refugees or asylum-seekers, often with horrendous backgrounds.

“I can’t even read their files any more,” admitted one Camden secondary-school teacher. “It upsets me too much.” At the same time, housing and travel costs are off the graph, making it a tough place for teachers to build a career.

As a result, structural problems remain entrenched. London finds it relatively easy to recruit young teachers, but hard to hang on to them. The average age of London’s teachers is only 30. Middle managers are thin on the ground, but if younger teachers are promoted early, “then you have a whole lot of knock-ons from that”, says Professor Alistair Ross, director of the institute of policy studies in education at London Metropolitan university. “The gaps won’t open up for younger people and you get a log-jam on promotions.”

Mortgage deals are on offer to London teachers, as is charter status, where a five-year commitment to the capital can bring cash rewards, and recruitment problems are easing. “But the sums still don’t add up,” says Ross. “There’s a need for much more long-term strategic thinking.”

Then there is the vexed question of secondary admissions. Parents heard the results of their applications for September entry this week. The capital is to get 20 new schools and 15 sixth-form colleges, but in a city where rich and poor families live cheek by jowl and competition for good places is practically a bare-knuckle fight, this is unlikely to erase the annual admissions scramble. What would help is a non-selective, city-wide system for allocating places, but that remains a pipe dream, not least because it will be so difficult to persuade affluent Londoners to use their local schools.

To be truly successful, London’s schools need a better social mix, but the proportion of the city’s parents who choose private schools is twice as high as parents elsewhere, and views such as that of the novelist Tim Lott, who wrote in the Evening Standard recently of his “hellish” search for a secondary school place, are common. “The truth is”, he wrote, “that in most of London, unless you’re rich, pious or a genius - you’re stuck.”

The Government is trying to pull back the middle classes through city academies. Thirty are planned for the capital, but they do not always succeed, and can go against the grain of other policies encouraging schools to co-operate. In Haringey, where Greig city academy has done less well than neighbouring schools, Sharon Shoesmith, director of education, says flatly: “We aren’t intending to have any more. We want to build on our collegiate atmosphere.”

John Bangs, head of education at the National Union of Teachers, says:

“When schools are trying to work together, it’s real destabilisation to plonk down a flag-waving institution, saying it’s the best school in the area, that isn’t tied in to any of the local partnership arrangements.” The NUT also says there is a need for a London-wide forum to address “significant gaps” in such areas as special needs provision, professional development and pupil-tracking.

“We know, for example, that lots of asylum-seeker children go missing when they cross borough boundaries,” says Mr Bangs. Other problems persist. The Government’s retreat from a unified system of education for 14 to 19-year-olds seems certain to exacerbate the capital’s deep social divides, while individual schools remain mired in difficulties. And while the Government’s London Challenge strategy, which has pushed energy and resources into secondary schools in the capital, is widely applauded, there are many, including Tim Brighouse, chief adviser to London schools, and the cheerleading face of the strategy, who feel the money behind it - pound;20 million in the first year, excluding school building costs - is nowhere near enough.

However, at school level, exciting things are happening. In Haringey, where results have gone up by more than 12 per cent in the past three years, Sharon Shoesmith says a focused local authority, “driven and passionate heads”, an emphasis on teaching and learning, and outreach into the community, are all bringing returns.

“We are 10 years into good quality research into school improvement and know how to apply it.”

Phyllis Dunipace, executive director of education for Lambeth, where GCSE results went up 6 per cent last year, says: “We have seen sustained improvement for a number of years and one reason is we have very, very good data. We have it on individuals and on groups and we use it to target achievement. We can say, ‘So-and-so is doing well with black Caribbean boys, why aren’t you?’” This kind of close forensic analysis is now being widely used in London.

“We know that groups that are not doing well are boys of Caribbean heritage, those from a Turkish-Kurdish background and white working-class boys, while children from Indian, Chinese, Vietnamese and Pakistani families seem to do much better,” says Alan Wood, executive director of The Learning Trust, which runs Hackney’s schools, where GCSE results went up 4 per cent last year. “We have to ask tough questions about this or we are going to let down a significant number of children.”

More attention to gifted and talented children, a greater use of IT in schools and a pledge to all London students to offer them artistic and sporting opportunities are also helping to personalise learning, while Bill Clark of Islington sees “the much closer partnership between the education authority and heads of schools” as one key to Islington’s success. “I think we’ve now got the culture right.”

Professor Kathryn Riley, of London university’s institute of education, an expert in urban schools who works closely with a number of London school improvement programmes, says this kind of detailed work changes both expectations and results. “What really enthuses teachers is collaborating and recognising how diversity can be a strength.” Schools in areas of high pupil mobility have also been heartened, she says, by looking more closely at their exam results and realising that they actually do well with those pupils they hang on to.

But she emphasises that effective school improvement takes time, resources and constant encouragement and focus. “A lot of good things are happening, but I’d say it is still very fragile. If you’re a head in this sort of challenging situation, no matter how good you are, you can never stop. You can’t say, ‘That’s the uniform sorted. Let’s move on to something else.’” Education chiefs in London are turning their attention to new areas - key stage 3 pupils, and the integration of children’s services - to keep standards rising, but they know that it will be statistically impossible to keep up the current rate of improvement, and that increasingly tough tasks lie ahead.

Meanwhile, London’s achievements are being trumpeted loudly by the Government in the run-up to the election. Schools standards minister Stephen Twigg said recently: “Our best urban schools are attracting international attention for leading school improvement.” He announced that the London Challenge strategy would be extended to primary schools.

But to those on the front line, government initiatives are seen as more supportive than central. “London schools are being transformed by London heads and teachers,” says Alan Wood. “And anyone else has to be very careful not to grab the credit.”

LONDON FACT FILE

* 51.7 per cent of 15-year-olds got five GCSEs at A*-C last year, up 1 percentage point.

* Two boroughs, Lewisham (up 6 percentage points) and Islington (up 7) are the fastest improving education authorities in England.

* Classroom teachers’ pay in inner London was pound;30,000 in 2002, nearly pound;6,000 more than in 1997.

* Number of teachers in London state schools in 2004 was 61,500 compared with 53,800 in 1997.

* Absence rate for London’s pupils was 7.83 per cent in 2004, down from 8.26 in 2003.

Source: DfES