The Colne is a river in England which is a tributary of the River Thames. Just over half its course is in south Hertfordshire. Downstream, the Colne is the boundary between Buckinghamshire (specifically the South Bucks district) and London (specifically the London Borough of Hillingdon) and finally between corners of Berkshire and Surrey. On leaving Hertfordshire, the watercourse splits off into several separate branches, a few of which rejoin it, and its main branch flows into the River Thames on the reach above Penton Hook Lock at Staines-upon-Thames.Two further, artificial distributaries were constructed in the 1600-1750 period for aesthetic reasons for Hampton Court and for Syon Park which have been kept maintained, flowing through several London districts. Although their main purpose was not drinking water, these artificial streams can be likened to the New River in scale and in date. Crossing its route, viaducts and canals, such as the Grand Union Canal have been recognised for pioneering engineering during the Industrial Revolution.