Chertsey is a town in the Borough of Runnymede, Surrey, England, 18 miles southwest of central London. It grew up around Chertsey Abbey, founded in AD 666 by St Erkenwald, and gained a market charter from Henry I. A bridge across the River Thames first appeared in the early 15th century. The River Bourne through the town meets the Thames at Weybridge. The Anglican church has a medieval tower and chancel roof.