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. 10/8/2009 Sinn Fein party meeting. Pictured at the Sinn Fein party meeting is Deputy First Minister Martin McGuinness(L) with President Gerry Adams, and Mary Lou McDonald at the Ard Boyne Hotel in Navan. Photo. Mark Stedman/RollingNews.ie