BERTIE Ahern stood down yesterday as Taoiseach (prime minister) of the Irish Republic. One of his last official actions was to join with the Rev Ian Paisley, Northern Ireland's First Minister, in an opening ceremony of a visitor centre at the site of the Battle of the Boyne in 1690. Many unexpected reconciliations have taken place in northern and southern Ireland over the past decade but none has been more remarkable than that between Mr Ahern and Mr Paisley. Anyone who understands the deep significance of the Battle of the Boyne for hardline Ulster Protestants will recognise how astonishing it is that these two men should have shared a visit to the site of the Battle as their final political act together. Mr Paisley himself is due to end his term as First Minister next month. The power-sharing agreement that has made peace possible in Northern Ireland owed a great deal to Bertie Ahern clear-sighted understanding of the absolute necessity for the Irish Republic to be supportive of it. If there had been the slightest doubt about his position it would have made the already difficult negotiations almost impossible. When he took office in 1997, at about the same time as Tony Blair, the IRA had still not committed itself to a sustainable cease fire. The subsequent progress was slow and sometimes painful but Mr Ahern was consistently positive in his attitude. Tony Blair has rightly received most of the praise for the successful outcome but Bertie Ahern's contribution should never be forgotten.