The water course that flows through the park, Costons Brook, is a tributary of the river Brent. Its source is difficult to identify since the development of Greenford these last 100 years or so have resulted in most of it running in underground culverts. The map I talked about here can help identify its original course, which appears to show one arm of the brook running close to Paradise fields, just west of Horsenden Hill.
To be absolutely certain that the stream there contributes to the Brook, dye can be dropped into it at a location in the new beaver enclosure. This was done in late December by Ben and volunteer friend of CURB (Clean up River Brent) and some 40 minutes later, you can see the result below, photographed at the point where the brook emerges from a culvert to finally flow in the open.
The result can be alarming to a passer by, but fear not – the dye is environmentally safe. When we first moved into the area in 1980, we discovered a fascinating history associated with the William Perkin’s dye works built in the 1850s and which Costons Brook appears to run past. Although Perkin is best known for his mauve dye (called mauveine), he also discovered a bright green dye which became known as Perkin’s Green. Histories of this period record how the local streams would occasionally run green, perhaps due to a failed batch of the dyes being dumped in them. Now we can see what this would have looked like.
There are plans to try the experiment again with other potential sources of Costons Brook, so keep your eyes peeled for more news.
Arrow 1 is the location of a substantial stream, visible at the western entrance to Greenford Birch Wood. Arrow 2 shows the location of an apparent tributary to Costons brook in the 19th Century map, a little south of the current stream.