The state-school system in Lambeth, south London, was pushed into the spotlight in the last week.
Shadow home secretary Oliver Letwin said he would rather "go out on the street and beg" than send his twins to his local school in Lambeth, which was subsequently identified as Lilian Baylis.
Now figures show it is the London borough with the highest number of pupils being taught outside the authority where they live.
Gareth Compton, deputy executive member for education on the joint Liberal Democrat and Conservative-controlled authority, said Mr Letwin's comments were based on perceived problems rather than reality. He said: "Clearly they were very unfortunate comments. It's a problem of perception.
Standards in Lilian Baylis are improving rapidly and I think they will continue to do so. But when a secondary gets a bad name it takes a long time for the reality to overcome the perception."
Gary Phillips, head of Lilian Baylis, said Mr Letwin had made his remarks without knowing about the school. He said he is proud of the school, which is one of the top 100 in terms of value-added. It has been awarded Artsmark Gold and the number of students gaining five A*-C GCSE grades rose from 6 per cent last year to 17 per cent this year.
He said: "I would like people to take a giant leap of faith in state schools. A lot more middle-class children are coming to the school, parents are coming to parents' evenings and telling us their children are happy here."
Mr Compton, a Tory councillor, said the issue of perception over reality also had an impact on the figures for pupils leaving the borough for school (see story right). He said: "We are extremely concerned about it. It really is the top priority for education in Lambeth."
He said the reasons for the exodus of local children were complicated but included the closure of a number of secondaries in the 80s and 90s and standards in some schools having been too low, though this was no longer true.
Today, even with all the secondary schools full, there were not enough places for all Lambeth's 11-year-olds.
He said: "With the improvements, these schools have to a greater extent won back parents' trust. There are still improvements to be made but we are moving in the right direction."