Sir Crispin Tickell, 76, director of the Policy Foresight Institute at Oxford university and former ambassador to the United Nations, spoke to The TES before addressing this week’s Association for Science Education Conference in Birmingham.

It was critical, he said, that children’s innate interest in the natural world was maintained through their secondary schooling - and that was better achieved through the breadth of the International Baccalaureate than through A-levels. He was urging his grandchildren to sit the Bac.

Before the war, he had been encouraged to learn outside the classroom. When he was seven, a cousin who ran London Zoo broke rules to allow him to take a lion cub home in a taxi for a day. He said: “It had very sharp claws, I remember.”

Now, children in cities were more likely to spend their afternoons sitting in front of the television and their school hours preparing for narrow and irrelevant tests.

“You do need to get exposed to wildness,” he said. “They get pushed into the tunnel of adolescence, taught whatever the conventional wisdom may be, then they go to university where some will get stuck in little specialities, which I think is very sad.”

He applauded an initiative, unveiled at the conference by the Woodland Trust and the University of Strathclyde, to involve children in phenology - collecting data about the arrival each season of the first bramble, the first horse-chestnut, the first ivy and more.

Sir Crispin’s call comes amid indications that Gordon Brown, the prime minister-in-waiting, is looking to set up a separate Department for Science.

Professor John Holman, director of the Government’s Science, Technology, Engineering and Mathematics programme, said the proposal would raise the profile of science in schools.