Longford River

The Longford River is an English artificial waterway, a distributary designed to embellish a park, that diverts water 12 miles (19 km) from the River Colne at Longford near Colnbrook to Bushy Park and Hampton Court Palace where, at both, it has outlets to the Thames, on the reaches above Teddington Lock and Molesey Lock respectively.

More information on the Wikipedia page