麻豆约拍

Many chocolate makers keep their innovations to themselves to protect their product. Emily Thomas is given a behind the scenes tour of Prestat, of London's oldest chocolatiers. Famous clients have included the Queen and Roald Dahl. Owner Bill Keeley tells Emily what measures are in place to keep their trade secrets.

(Photo: White truffles on a conveyor belt Credit: 麻豆约拍)