At the Gloucester Street Bridge (in the photo), the Churn divides, left towards Barton Mill and the Gunstool Brook. Right via sluices along the Abbey Way.
This is quite a confusing subject....
Here are some notes from an article by Richard Reece and Peter Broxton on Cirencester streams, CAHS Newsletter 2011.
- Water enters Cirencester via the Daglingworth Brook and the River Churn.
- Originally, the two streams ran either side of a gravel island, on which the town was later built, until they met in a marshy swamp at Watermoor. (See Map 1) The natural course of the Churn was probably through the Abbey Lake and out behind Purley Road. A geophysical survey in the Abbey Grounds may have discovered its original course.
- In the Roman period both streams were both canalised round different sides of the wall to meet to the SW of the town (Map 2)
- In the Medieval and post-Medieval period the Daglingworth Brook flowed direct to Barton Mill. It continued in an artificial course, via the swimming Baths (Gunstool Brook), behind Coxwell Street, under the hump at the Gosditch Street/Dollar Street junction [site of the Abbey Mill]. Then took the Abbey effluent out towards Watermoor. Fed Langley Mill. The original course of the Abbey stream is now lost because of the School Field and railway embankment, but can be seen on 1795 and 1835 maps.
- The Romans built new higher course for the Churn along Grove Lane outside the walls. No water was allowed to escape until it rounded City Bank and fell into Watermoor. Gave New Mills a prime location. The Furnes Hole (?still visible in CB) allowed water to run off into City Bank and feed Langley's Mill. Added to the flow it already received from Gunstool Brook.
- Mills: In Domesday there are three mills - Barton Mill, Langley's Mill and a third, the site of which is now unknown.
- An additional Medieval watercourse is referred to by Leland, and later Rudder: it ran along Gloucester Street, Dollar Street, down Gosditch street by the Ram Inn and then down Cricklade Street and finally out into Watermoor. (So did this run in a channel down one side of the road?)