Dollis Brook, runs through the London Borough of Barnet in north London. It is a tributary of the River Brent, which is itself a tributary of the River Thames. The Dollis Valley Greenwalk follows almost all of Dollis Brook, apart from a short section at the beginning which passes through private land, and the London Loop follows it as far as Barnet Lane. The name Dollis is probably derived from the Middle English word 'dole', meaning the shares of land in the common field. More information on the Wikipedia page [1].