On The Runs: Collapse of trial blew lid off scandal which threatened to bring down Stormont
The on-the-runs controversy burst onto the news agenda after the collapse of the Old Bailey trial of John Downey.
Mr Downey had been due to be tried for the murder of four soldiers in the IRA's Hyde Park bombing in London in 1982.
But a judgment by Mr Justice Sweeney revealed details of a secret arrangement to deal with IRA suspects who were on-the runs (OTRs).
The OTRs were seen by Sinn Fein as a peacetime 'anomaly' that needed resolved - had they been in prison before 1998, they would be free under the Good Friday Agreement.
With the Blair Government anxious to get Sinn Fein to buy into support for the police, it believed it needed to address the issue to keep republicans on board. The issue was raised at the Weston Park talks in 2001, but disappeared after opposition to what some saw as a general amnesty.
There were concerns in Belfast and London that such a move would have undermined the rule of law, and - because it would have applied to the security forces - equated soldiers with terrorists, or legitimised the IRA campaign.
As attempts to deal with OTRs floundered in public, it would later emerge that fugitives had been quietly sent 'letters of comfort' assuring them that the police were not actively seeking them.
The letters were seen as another way to deal with fugitives after earlier legislative bids had failed in 2006. Tony Blair would write to Gerry Adams that year, assuring him the Government was "expediting the existing administrative procedures". Mr Downey was sent one of these letters, but in error. It was, however, enough to scupper his trial. The existence of the letters sparked unionist fury, with claims that the administrative scheme involving the NIO had been set up behind their backs.
Peter Robinson even threatened to resign as First Minister unless there was a judge-led inquiry. He didn't get one - nor did he quit - but two reviews were ordered to mollify unionist concerns. The first review led by Lady Justice Hallett reported last year how there were "systematic flaws" in the operation of the "unprecedented" scheme. She found that the on-the-runs scheme was not designed, but evolved, and lacked accountability and safeguards. Despite its haphazard nature, she said it was not unlawful.
Because the OTR letters scheme began while Mr Blair was premier, the chairman of the Northern Ireland Affairs Committee believed he would be one of the most important witnesses to Westminster's own inquiry.
But Mr Blair would prove difficult to pin down. Having brought peace to Northern Ireland, the former PM was now trying to do the same in the Middle East, with his diary apparently too full to appear before MPs. He believed his presence was unnecessary, as he had already given evidence in private to Lady Hallett and had nothing new to say. Mr Blair managed to resist the Northern Ireland Select Committee for nine months.
It was reported Mr Blair had appealed to Commons Speaker John Bercow to be allowed to avoid MPs' questions. It is understood Mr Bercow made it clear that Parliament would take a very dim view of any refusal to do so.
The next day, the committee was told Mr Blair would appear.