DOLLIS BROOK IS one of the two main tributaries of the River Brent, which in turn is a tributary of the River Thames, which it enters at Brentford. Dollis Brook rises near the A1 dual-carriageway at Mote End Farm and then flows southwards towards Brent Park, where it is joined by another stream, Mutton Brook. Both brooks are lined with pleasant green spaces containing footpaths that follow the streams. Thus, they are lovely green corridors providing much-needed rustic relief from the relentless built-up suburbia through which the streams flow.

Nether Street is road running west and downhill from Finchley Central Underground Station. After reaching a small roundabout, it continues as Dollis Road. The latter descends ever more steeply until it runs under a tall brick arch, part of the Dollis Brook Viaduct (also known as ‘The Mill Hill Viaduct’). The road runs beside a stretch of Dollis Brook, which at that location is only a few feet in width – rather a miserable little stream. However, the viaduct with its 13 arches, each with spans of 32 feet, traverses a veritable steep sided gorge, maybe created over time by the waters flowing in the humble Dollis Brook, or, more likely, by glacial drift (“Nature”, 9^th of November 1871: http://www.nature.com/articles/005027c0.pdf). This amazing viaduct, a masterpiece of brickwork, carries Underground trains on a spur of the Northern Line running between Finchley Central and Mill Hill East stations.

Designed by John Fowler (1817-1898) and Walter Marr Brydone, who was Engineer-in-Chief for the Great Northern Railway (‘GNR’) from 1855-1861, the viaduct was constructed between 1863 and 1867, when the first train ran across it. The line that now carries Northern Line trains over the viaduct was originally built by the GNR, as was the viaduct. As trains traverse the viaduct, they are at one point 60 feet above the ground. This point must be close to where both Dollis Road and Dollis Brook pass beneath the arches,

We have often driven beneath the viaduct, but it was only in August 2021 that we decided to park near it and examine it as closely as we could. We had recently visited the impressive granite railway viaduct near Luxulyan in deepest Cornwall and been amazed by its grandeur. We had not expected to find a bridge in north London that is almost as awe-inspiring.  As I gazed upwards at its tall arches, I admired the Victorian bricklayers, who must have had to work at ever-increasingly dizzying heights as they constructed it. The viaduct is certainly a sight worth seeing, and whilst you are in the area, much pleasure can be gained by taking a stroll along the paths that run close to Dollis Brook.