Sinn Féin's Youngest Lord Mayor Resigns from Irish Senate for Health Reasons
• Sinn Féin senator Niall Ó Donnghaile has resigned from the Irish senate for health reasons
• He was a member of the senate since 2016 and previously a councillor in Belfast
• In 2011 he served as Belfast's youngest ever lord mayor at age 25
• He has been unable to attend the senate since the summer due to doctor's advice
• Sinn Féin leader Mary Lou McDonald said he provided a "valuable contribution" on the Good Friday Agreement