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. 25/03/2016 Sinn Fein Easter 1916 Centenary Commemorations taking place this weekend. Good Friday - 25th March. Lost Leaders march. A historical cortege will be departing from Kilmainham Gaol and heading to Arbour Hill. Gerry Adams will be the main speaker at the event.1916 Relatives and members of the public and other guests of honour attending the Sinn Fein Easter 1916 Centenary Commemorations of the Lost Leaders march. Pictured are (LtoR) Gerry Adams and Mary Lou McDonald at the Lost Leaders march. Photo: RollingNews.ie