Clare Balding joins singer Feargal Sharkey for a river walk on the south London/Surrey border along the River Hogsmill one of just 200 chalk streams in the world. He's always been a rambler and is currently walking all of the river routes of London. He is often dismayed and pleased in equal measure at the state of our rivers as he is a passionate advocate for water health and quality.
The walk is part of the London Loop and starts from Ewell West Station and ends at Kingston upon Thames passing through Old Malden.

Producer: Maggie Ayre