ITV showed The Words of War on Tuesday 11 November 2008. From the ITV website:
"This year marks the 90th anniversary of the signing of the Armistice which ended World War One on 11th November 1918. Britain declared war on 4th August 1914 and almost one million Britons lost their lives during 1,297 days of conflict. We chart the course of the war through the writings, letters and poetry of British combatants, painting a moving picture emphasising the need for remembrance."
Thanks to timmytiger who realized that Matthew Macfadyen was narrating this documentary.
The ITV webpage is here. You can also watch it on ITV's catchup feature for those in the UK