Rolf Harris has been singing Two Little Boys for 40 years. Until now, he had no idea just how much the song mirrors the story of his dad and uncle in the Great War. In this programme, Rolf fulfils a lifetime's ambition by travelling to the Western Front to find out the truth behind his hit song. Kirsty Wark, meanwhile, uncovers the brutal reality of her great uncle's life in the machine gun corps.

• Kate Silverton
• Kirsty Wark