This former Hop Farm at Beltring in the heart of the Kent countryside has the worlds largest collection of oast houses and was the centre of the area's brewing industry until 1984.
Ale has been brewed in England since Roman times if not earlier. Ale is brewed without hops, beer is brewed with hops added. Since the 16th century when hops were introduced to England, and to beer, it has been an important commodity and vital to the local economy. At one time Kent had over 30,000 acres devoted to the growing of hops.
This website has some interesting history: http://www.britainexpress.com/History/oast-houses.htm