A headteacher who was made a Dame for her achievements has released a book about the experiences of more than 50 of her pupils.

Former students at Hampstead School, Cricklewood, were asked to contribute a short piece about their time at the Westbere Road school and how it changed, or helped them, in later life for the book, Comprehensive Achievements: All Our Geese Are Swans.

It is a series of love letters to the Camden comprehensive, compiled by Dame Tamsyn Imison, who was headteacher of the school for 16 years from 1984 until 2000.

The book has been endorsed by White Teeth author and former student Zadie Smith and film producer Lord David Puttnam.

Mrs Imison, who does not like to be styled as Dame Tamsyn, said the book’s unusual title comes from a comment made by the first headteacher she worked under. “In my first job, I was given responsibility for the seventh stream group,” the 77-year-old Suffolk resident said.

“I don’t believe in a steaming system. I said to [the group], you are going to come top of the exams, you are perfectly capable of it. They didn’t come top but they did come second. As a result, the school changed from streaming to a broader [system] with mixed ability groups.

“The head said, the trouble with you, Mrs Imison, is that all your geese are swans. I didn’t say it at the time but I thought, ‘well, I’m damn glad all my geese are swans’. That comment has always stuck with me.”

It was her belief in the capabilities of every student that transformed Hampstead School into an academically successful institution, as well as a happy and vibrant place to study.

“If you believe in everybody, you will see miracles,” Mrs Imison, a member of the National Advisory Committee on Creative and Cultural Education, added.

Mrs Imison said the book is a “celebration” of comprehensive education, of which she has always been a passionate advocate.

When then Prime Minister Tony Blair made her a Dame Commander of the British Empire in 1998, she accepted it only because the honour was a recognition of the achievements made by all comprehensive headteachers.

Zadie Smith wrote of the book: “I have always considered myself extremely lucky to have attended Hampstead School, a fact hard to explain to the sort of people whose interest in a school begins and ends with its league tables.

“It’s a pleasure to be able to hear so many former students expressing the complexity of that experience; what it meant to them to be in a school that believed everyone deserved at least the same opportunity – whatever their ability, class or race – and for free.”

* Comprehensive Achievements: All Our Geese Are Swans can be purchased from Hampstead School and bookshops.