town (parish), Chiltern district, administrative and historic county of Buckinghamshire, England, in the Misbourn River valley. The wide High Street of the old town is flanked by half-timbered coaching inns, Georgian houses, and a 17th-century town hall. The parish church of St. Mary dates from the 14th century. Amersham lies on a main rail line from London (26 miles 【42 km】 southeast) and has attracted commuters. Pop. (2001) 21,470.