John McIntosh, head of the school where Tony Blair sent his children, is retiring after 29 years in the job.
Mr McIntosh has been head of the London Oratory school, in west London, since 1977.
Though he has been careful not to discuss the affairs of his famous charges in public, he has nonetheless been critical of many of Mr Blair's public and private decisions and has been a controversial and influential figure in education.
The 59-year-old, who steps down next summer, insists that the Blair connection is only a small part of his long career. "There are some pupils you remember, just because of their circumstances," he said. "But others you remember for their strong characters."
His school was in the vanguard of the opt-out movement during Margaret Thatcher's Conservative government in 1989.
"That was my happiest period," he said. "I think schools function much better if they have a high degree of autonomy. So I'm very optimistic about the principles for school autonomy outlined in the recent white paper."
And when in 1994 Tony Blair, then Labour's leader in opposition, chose to send his elder Euan there, rather than a local north London school, many Labour supporters felt betrayed because he had chosen a grant-maintained sector.
But Mr McIntosh rode that controversy and showed he was not adverse to ploughing his own furrow, despite his high-profile pupils.
In 1999 he revealed that Mr Blair's sons, Euan and Nicky, would miss the first day of term, because they were on holiday with their parents in the Seychelles.
This emerged less than a week after David Blunkett, then education secretary, had said that children should not be allowed to skip school for term-time travel.
And, when the Blairs hired private tutors for their sons, Mr McIntosh suggested to friends, who in turn suggested to the media, that "private tuition can make children neurotic".
In 2000, he was criticised by inspectors for failing to avert a pound;250,000 budget deficit.
He was subsequently forced to send a letter to parents, asking for a monthly contribution of pound;30. And, last month, the Oratory hit the headlines as the only state-funded day school in England to defy the Government's ban on selection by interview. Mr McIntosh, who believes that interviewing enables him to accept pupils from across the social spectrum, challenged the ruling in the High Court, and won.
"Anything worthwhile has to be fought for," he said. "You fight as hard as you can. That's what every head should do."
The voluntary-aided Catholic school educates 1,370 pupils, ranging from seven to 18 years old. There are 80 girls in the sixth form, including Mr Blair's daughter, Kathryn.
It is one of the country's top-performing comprehensives, with 93 per cent of pupils achieving five A*-C grades at GCSE this year. And it is renowned for its music education.
Schola, the school choir, has a performance history ranging from vespers at Chartres cathedral to the soundtrack for the 1998 film, American History X.
"The music is very special," said Mr McIntosh. "I'm proud of it. But now I'm looking forward to having a proper holiday. I don't think I've had one for 29 years." The advertisement for his successor appears in this week's TES.
Sandy Adamson, director of education for the Oratory's borough of Hammersmith and Fulham, said: "In a way that famous football managers find difficult, John has kept the Oratory near the top of the league table for over a quarter of a century. He has a clear and unswerving understanding of the business, pays constant attention to detail, and has never taken his eye off the ball."
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