Gregg Wallace explores the Farrow & Ball factory in Dorset to learn how they produce up to 200,000 litres of paint and 10,000 metres of wallpaper a week. They make 270 different coloured paints, but Gregg is learning how they make ‘sulking room pink'.Meanwhile, Cherry Healey discovers how a key ingredient in the paint-making process is mined at a huge china clay mine in Devon and learns the art of hanging wallpaper at a DIY school.And Ruth Goodman is in the Lake District, exploring the history of wallpaper, and visits Portsmouth to uncover the extraordinary story of how ships in the First World War were painted with dazzling patterns to evade German submarines.