From the Wikipedia page [1] The River Beck is one of the tributaries of the River Ravensbourne in south London. The source of the River Beck is in Spring Park (grid reference TQ377647) where Shirley and West Wickham meet. For its first mile or so it forms the border between the London boroughs of Croydon and Bromley. Indeed, historically, this was also the border between Surrey and Kent. It gives its name to Beck Lane, Elmers End and Beck Way, Beckenham.