The Great War of 1914-1918 now stands at the furthest edge of living memory. And yet, hardly a month passes without some dramatic and sometimes tragic discovery being made along the old killing fields of the Western Front. Graves of British soldiers buried during battle - still lying in rows seemingly arm in arm or found crouching at the entrance to a dugout; whole 'underground cities' of trenches, dugouts and shelters have been preserved in the mud;...