BBC News NI political correspondent

The murder of three off-duty Scottish soldiers in Belfast by the IRA 54 years ago is a “scar that has never healed and never will,” one of their families has said.
The Scottish soldiers were John McCaig, 17, his brother Joseph, 18, and Dougald McCaughey, 23.
They were found shot dead in Ligoniel, north Belfast, on 10 March 1971.
The Royal Highland Fusiliers had been drinking in a city centre pub when they were lured to their deaths by the IRA.
Their story was raised by the cousin of Mr McCaughey at an event at Stormont on Monday, marking European Day for Victims of Terrorism.
David McCaughey said his family deserved answers, saying it had been a “long, long road”.
He said what should normally be a happy time of year with his son’s birthday today, had been overshadowed by the phone call that changed his family’s life.
“All that we want is the truth – that’s not too much to ask for, is it?”

The event, running for the 13th year, was organised by TUV assembly member Timothy Gaston.
Those who took part also heard from Caroline D’Eath, the daughter of Gerald D’Eath, who was 31 when he was killed by a UVF bomb while working on a building site in 1975.
Ms D’Eath said it was the first time she was sharing her family’s painful story.
Mr D’Eath, who was a bricklayer from Dungannon, had been working on the site of a new Christian Brothers school in Glengormley in County Antrim.
No one has ever been arrested over the murder.
He had a wife and three young daughters.
‘Our lives changed forever’

Ms D’Eath said she was only four years old at the time of his death and had no memories of him.
“In that moment our lives changed forever – these people took away my father and a beloved husband,” she added.
“He never got to see any of us grow into the women we are today, he never got to walk any of us down the aisle.
“The government’s legacy act serves no purpose, the aftermath is still very traumatic. Everyone just wants truth and justice, they want the future to change.
“My mother died nine years ago never getting any justice. 50 years later we have lots of unanswered questions about my father’s murder and it rubs salt in our wounds even more that no one may ever be brought to justice.”
Pamela Wilson, whose father, RUC constable David Consett died in an IRA bomb in 1973, told the event that her mother and brother never recovered from the trauma and are both now dead as well.
She criticised the Troubles Legacy Act and the fact that she and her sister were deemed ineligible for the Troubles pension.
The event also heard by video from Collette Murray, whose brother Cyril was shot dead by loyalists in July 1992 in a case that was later deemed mistaken identity.