Burntwood School for Girls in the London borough of Wandsworth has a logo: a striking image of a tree against a rising sun, which adorns the bright red sweatshirts worn by the pupils. But it also has a true corporate identity: a sense of everybody working together to provide, in the words of the school’s mission statement, “the best education today for the women of tomorrow”.

It is an identity forged against the odds. The school was created in 1986 by amalgamating two schools - Garratt Green and Mayfield - on the Garratt Green site. One had streaming, uniform and firm discipline, while the other had mixed-ability teaching, no uniform and highly developed pastoral care. Both had poor results: about 17 per cent of their pupils got five or more grades A-C. Today, nine years later, the figure is 47 per cent.

How was that done, against an inne- city background? The school’s spacious, well-maintained campus, a prize-winner in the 1950s, should not mislead visitors. Half of Burntwood’s 1,500 pupils come from economically deprived areas and 40 per cent speak a language that is not English. Each year, about five girls enter the school unable to read.

“The schools were so different they were irreconcilable,” said Brigid Beattie, the principal who has led the school since 1986. “We had to start again. ”

The organisational problems were immense: it took four years to get the two schools on to one site. Some staff left, 28 were redeployed to other inner London schools, and two surplus deputy heads have since “peeled off”.

Barely were they all on one site than the school decided, with the support of 80 per cent of the parents, to opt out in 1992.

Burntwood did not want to follow Tory Wandsworth’s policy of specialisation, but preferred to continue to provide a broad education for its girls. This autumn, it introduced another change: admitting 30 per cent of pupils on the basis of selection. “If we hadn’t,” said Mrs Beattie, “we would have become a sink school pretty rapidly.”

She stresses the importance of creating rituals and symbols for the school, such as the red and grey uniform introduced after a poll of parents and pupils - and against the wishes of staff.

But rituals and symbols get you nowhere without an underlying ethos. At Burntwood, it is the high expectations everybody has of everyone else, from the headteacher down.

Mrs Beattie acknowledges that her teaching experience in Hampstead and at Henley Grammar School may have been significant here, showing her what could be achieved by “bright pupils from supportive homes”. But she thinks the quite different experience she gained at a Haringey comprehensive and as deputy head of Holland Park, both in London, was just as important.

“I do think it’s very easy to succumb to the social worker philosophy, ” she said. “That’s all right for one child, but not for a class of 30. I’ve seen a lot of caring schools in London that achieve abysmal results and I was determined to avoid that.”

Success Against the Odds, published by Routledge, price Pounds 8.99, is available from bookshops or telephone 01264 342923