A man throws up in a taxi on his way to an interview. He is nervous because he is about to make an argument. It’s an argument that would change politics forever.

His name was Keith Joseph. And this would be the start of a radical journey - from conventional conservative politician to ideological warrior and guru for Margaret Thatcher. Joseph set out on a tour of the country. He had eggs thrown at him, Marxist flags waved in his face. He was spat at. Heckled. All because he was arguing for one thing - the free markets.

David Dimbleby traces the history of an idea that spans his life. It started on a chicken farm in Sussex, gained traction in the shadows of post-war London and rose to heights of excess in the new champagne bars of the City. It's 2025 and this once radical idea now defines every aspect of life in Britain. An idea that transformed the economy, politics and, ultimately, society itself.

But how did it happen? Who are the little-known people behind it? What did they want? And - as Donald Trump threatens to overturn the global economic system - is the free market here to stay? Or are we entering a new era?

Presenter: David Dimbleby

A Samizdat Audio production for BBC Radio 4