Sir Martin Sorrell has spent the last three decades transforming a maker of wire shopping baskets into the world's largest advertising firm. The self-proclaimed workaholic bought a stake in Wire and Plastic Products plc in 1985 and has since taken the advertising world by storm with a string of major acquisitions.

His meteoric rise is not without controversy. He is known for his relentless work ethic, punishing schedule, and ruthless approach to business. He has engaged in bitterly hostile takeovers, falling out with his competitors along the way.

The business has made Sorrell a wealthy man. This year his salary is expected to hit £70m, a sum which he has no qualms defending. Sir Martin believes he is "worth every penny".

Mark Coles speaks to Sir Martin Sorrell's childhood friend Simon Schama, his wife Cristiana Falcone and his colleagues and competitors, to reveal how he became the world's most powerful ad man.

Presenter: Mark Coles Producer: Ben Crighton.