Continuing his quest for understanding, David Baddiel explores derivatives. What are they and how do they work?

David begins by meeting journalist Janice Turner, who initially suggested the subject, and she explains why she believes we should all try to understand derivatives.

Then David visits the London Metals Exchange, the last place with open outcry trading in London, where he discusses the history of derivatives with financial historian D'Maris Coffman. And on a trading floor at Canary Wharf he hears how the market works today.

At the end, he returns to try to explain to Janice what he's learned, with D'Maris ready to pass judgement on his understanding.

Producer: Giles Edwards.