English: Longford River in Feltham The Longford River is an artificial watercourse constructed in 1638 at the instigation of King Charles I to improve the water supply to Hampton Court Palace and to provide a source for the water features in the landscaped gardens. It takes off from the River Colne at Longford and runs for about 19 kilometres, before discharging into the River Thames. The white noticeboard on the right advises that "The Police have received instructions to take into custody any person found trespassing, damaging or destroying the banks or the freeboard of the River. By Order." So there... Incidentally in this context the freeboard of a watercourse is the vertical distance between the water level and the level at which the water would burst one of its banks in a flood event.