The Pinn was at one time also known as Ruislip Brook, once this was a good fishing stream. In 1804 there was a right of way three feet wide along the banks of the Pinn so that the lord of the manor and his lessees and servants could enjoy the fishing, in those days there was far more water in the Pinn.

As the various channels of the Colne approach the Thames they spread out across an ancient alluvial fan. This broad deposit of gravel and sand was formed during the ice age and is somewhat higher than the ground to its east. This has allowed radial distributaries to drain eastwards towards the Thames. Extending six miles from Staines to Sunbury, the River Ash is the easternmost of the natural channels of the Colne  providing a important wildlife corridor through the western fringes of London. The nearby Sweeps Ditch also preserves the radial pattern, both watercourses have been greatly modified by human activity but fortunately they have survived as valuable features of the ancient landscape.

In previous centuries, travellers on the highway from Kingston to Windsor would have been familiar with the ford across the Ash which gave the Saxon parish of Ashford its name.The ford is now gone but a century ago it was a still beauty spot for the Edwardian inhabitants of Ashford. The marshy meadows beside the river were liable to winter flooding and the parish church is wisely situated on higher ground over half a mile from the ford itself.

The Duke of Northumberland River was first constructed during the reign of Henry VIII to augment the flow supplying existing mills and to supply new mills. The Longford River was constructed in 1638/39 at the instigation of Charles I  to bring water from the River Colne to augment the water supply to the Royal Parks at Bushy Park and Hampton Court.

Sweeps Ditch was originally fed by water flowing from the Colne via other small channels north of Staines. The historic mapping evidence suggests that it had two arms, one flowing west back into the Colne and one flowing east into the Thames.  So the natural source of Sweeps Ditch is the Colne.

Sweeps Ditch kept a culvertised connection to the Colne until the mid-20th century when the connection was totally lost during the contruction of the Two Rivers shopping centre. Presumably due to the historic importance of the channel, the borough decided to preserve it as a landscape feature. It is now fed artificially with water pumped up from the Thames.  So the present source is artificial.

Sweeps Ditch finally lost its connection to the Colne only a few decades ago.  But its decline probably began in the 1840's.  When the railway was built, it appears to have made use of the clear corridor of land beside the ditch. This would have raised the profile of the ground and restricted water flow. The custom of retro-fitting infrastructure into west London river valleys continues to this day. 

Explore your local river

There are many attractive walks along our rivers and other waterbodies in the Colne Catchment. Walks along the River Pinn can be found here.