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. 18/11/2017. Sinn Fein Ard Fheis.Pictured is Deputy Party leader Mary Lou McDonald speaking at the Sinn Fein Ard Fheis in the RDS In Dublin today. Photo:Leah Farrell/RollingNews.ie