Gregg Wallace gets exclusive access to one of the largest fresh milk processing plants on earth to see how they get milk from cow to carton in less than 24 hours. He reveals how one factory can process 2,000 litres of milk in under a minute and visits the hi-tech British farms where the cows are milked entirely by robots.Cherry Healey discovers how milk is used to make cheese and ice cream on an epic scale and reveals why most people in the world actually can't drink milk - and what makes us unusual in Britain.Historian Ruth Goodman investigates our complicated history with the white stuff and discovers just how tough it would have been to work as a dairy maid.