For centuries, walled gardens have provided a wealth of food, fruit and flowers for our great houses. Beginning as simple medieval enclosures, they evolved into powerful status symbols and centres of world-class horticultural expertise. Yet during the 20th century their fortunes failed, and most were lost or abandoned, as were many of the skills needed to run them. Happily, today many have been revived. Hudson is an archaeologist and historian who presents the BBC hit series Escape to the Country and Countryfile.