Simon Harris, the anointed successor to the outgoing Irish Taoiseach Leo Varadkar, has quite the in-tray. Harris, who was the only candidate in Fine Gael’s party leadership race, will become Ireland’s youngest prime minister on 9 April when the Irish parliament, the Dáil, resumes after its Easter break. One of the most pressing tasks he faces is trying to rebuild a semi-decent relationship with the unionists of Northern Ireland, such is the noxious legacy of his predecessor.