This watercourse is known as Dauntsey Brook until it is joined by the Wilts and Berks Canal spillway, just west of St James. From this point onwards the name changes to The Bourne. Despite the name change, the vast majority for the watercourse’s contents are supplied by Dauntsey Brook.
Dauntsey Brook has two main sources, the first from the east (Grittenham and Great Wood) and the second from the south (Wait Hill Brook and Bowd’s Lane).
If Brinkworth Brook overtops, flow travels westwards between the M4 and Grittenham into Dauntsey Brook. At the same time, the Whitehill Lane floods by Ivy Lakes and at the ‘T’ junction where the road crosses the M4 towards Brinkworth – when this occurs, the road becomes impassible to cars.
Water initially flows north under the motorway east of Dauntsey, under the bridge at Old Sodom Lane (a pinch point), through The Green, under the northern side of Church Lane and back south under the M4 again.
The Wilts and Berks Canal spillway flows under the road and then along the western side of St James. At this point it becomes Main River and known as The Bourne. This stream then meets Dauntsey Brook close to the M4, and from that point onwards everything is called The Bourne.