Slough is a town in Berkshire, England, in the Thames Valley 20 miles west of central London and 19 miles 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 Census, the population of the town was 143,184. In 2021, the wider Borough of Slough had a population of 158,500. Slough borders the ceremonial counties of Greater London and Buckinghamshire.