Alan Titchmarsh reveals some surprising facts about Beatrix Potter. Plus a rare plant nursery, a time capsule and the UK's largest seal colony.

Alan Titchmarsh, with celebrity experts and enthusiasts, reveals the hidden treasures to be found at Britain's historic houses and estates. Alan visits Quarry Bank Mill in Cheshire, an 18th-century cotton mill that is still home to a working mill as well as a museum. Oz Clarke uncovers some Civil War history at Dunster Castle in Somerset. Jon Culshaw visits a stately pile in an unusual location, Dan Jones joins an architectural dig on the south coast, and Clive Aslet visits the spectacular grounds of Biddulph Grange in Staffordshire.