Slough is a town in Berkshire, England, in the Thames Valley, 20 miles (32 km) west of central London and 19 miles (31 km) north-east of Reading, at the intersection of the M4, M40 and M25 motorways. It is part of the historic county of Buckinghamshire. In 2021, the population of the town was 143,184. The wider Borough of Slough had a population of 158,500.