Mary Lou McDonald - Leader, Sinn Fein

Stephen Sackur is in Dublin to meet Mary Lou McDonald, the leader of Sinn Féin - the party of Irish Republicans in the Irish Republic and in Northern Ireland. Ireland is going through a period of extraordinary change, with social attitudes shifting profoundly on abortion, gay rights and the role of the Catholic Church. Now Brexit poses a challenge to the island, both north and south, can Sinn Féin take advantage?