A unique wet woodland on the Grand Union Canal – London

Pull on your wellies for a swampy summertime walk in London’s Middle Earth

Peter Reed Flickr


Way out to the west of London, alongside the Grand Union and almost touching the M25 in Uxbridge sits one of London’s most spectacular areas of woodland. Denham Lock Wood makes for a fascinating visit at any season and you will be rewarded with some magnificent sights. This SSSI supports some of the finest examples of wet woodland in Greater London. Some of that is to do with the presence of water, with the confluence of canals, lakes and rivers of the Colne Valley providing a rich habitat for birds, flowers and invertebrates. It can get damp though, so take your wellies.

You can access the wood via the Grand Union Canal towpath at Denham, as the canal passes by aqueduct over the top of Frays River, which flows into the Colne at Denham Lock. This is the deepest lock on the Grand Union, with a drop of some 11 feet, and there’s a pleasant tea-room here for those seeking a pre- or post-walk cup of something warming.

The woods feature a wide variety of bird, plant and insect life including glow worm, red-headed cardinal beetle, banded demoiselle and the rare Desmoulin’s whorl-snail. Among its wild flowers you’ll find guelder rose, purple loosestrife, meadowsweet, dog’s mercury and marsh-marigold. A colony of water voles live in the woods and there may also be otters. “We see evidence of otters almost everywhere here,” says Mike Waller, ecologist of the London Wildlife Trust. “It’s a very wet woodland, much like a swamp, so we have boardwalks for people to get around. It’s a real water world. It’s draped in mosses, lichen and ferns, it’s like a scene from The Lord of The Rings.”