RN Collection: Mary Lou McDonald. Sinn Fein Vice President, Mary Lou Mc Donald, will be elected as the new leader and President of sinn Fein, to succeed Gerry Adams, in February 2018. End. 10/02/2017. Sinn Féin Deputy Leader Mary Lou McDonald outside Leinster House (Dail/Parliament) as she comments on the revelations contained in last night’s Primetime programme about Sergeant McCabe. Photography: RollingNews.ie