Thatcham is a market town and civil parish in the West Berkshire, England. It is situated in the valley of the River Kennet 3 miles (4.8 km) east of Newbury, 14 miles (23 km) west of Reading and 54 miles (87 km) west of London. The town has a long history dating back to prehistoric times, a claimant to the title of oldest continuously inhabited place in Great Britain. As of 2021, it had a population of 25,464, though it is part of a built-up area comprising itself and neighbouring Newbury of over 70,000 residents. It is on the route of the A4 Bath Road, the historic main road between London and Bristol.