David Walsh - Chief Sports Writer, Sunday Times, UK

Stephen Sackur speaks to Irish sports journalist David Walsh, who was convinced that cycling's untouchable champion Lance Armstrong was a drugs cheat long before the sport revealed the scale of his deceit. Armstrong is history of course, but doping continues to devalue elite sport; maybe it is a problem no amount of truth-telling journalism can fix.

It is the job of the journalist to speak truth to power, but can defying conventional wisdom and the powers that be often mean the profession can be a lonely place for many?