Michael Portillo returns with an authored documentary, that uses British state papers to shed fresh light on key events and personalities during the Civil War period in Ireland.

On the 22nd June 1921, King George V and Queen Mary arrived in Belfast for the official opening of the first Northern Ireland parliament. Fearful for their lives, they had come to a city scarred by bitter sectarian violence. The King’s visit to Belfast was the culmination of three centuries of history – and three years of political brinkmanship and brutal communal violence. The occasion marked the creation of the new state of Northern Ireland. A line had been drawn on the map – a new border that separated the north and south of the island. One hundred years on, this is the story of the dramatic events that led to the partition of Ireland - one that continues to reverberate to the present day and to dominate relationships between the islands of Britain and Ireland. (BBC Genome)