A member of Sinn Féin for 20 years, the year-old has been named as the successor to Martin McGuinness as the party's leader in the. The daughter of a former IRA prisoner has been unveiled as the new leader of Sinn Fein in Northern Ireland. Michelle O'Neill, who currently. Sinn Féin has announced that Michelle O'Neill is to replace Martin McGuinness as its leader north of the border. She had been widely tipped as.