THE previous Labour government wished for the release of Abdelbaset al-Megrahi, the Libyan convicted of the worst ever terrorist attack in Britain, who was sent home from a Scottish prison in 2009. It did “all it could” to secure that outcome—even if that wasn't much. So concluded an inquiry led by Sir Gus O'Donnell, Britain's most senior civil servant, whose report was published on February 7th.

Mr Megrahi was jailed in 2001 for planting the airline bomb that killed 270 people when it exploded over the Scottish town of Lockerbie in 1988. In 2009 the devolved government in Edinburgh released him on compassionate grounds: Mr Megrahi was cancer-stricken and said to have only a few months to live. He is still alive in Libya. The decision was controversial, provoking particular ire in America, whose citizens accounted for many of the Lockerbie deaths.

Gordon Brown, the prime minister at the time, has always insisted that the decision was taken by the Scottish administration alone—a position that the Scots, keen to emphasise their autonomy, have echoed. The report finds no evidence of London pressuring Edinburgh to release Mr Megrahi. But there was “an underlying desire” to see him freed; Britain advised the Libyan government on how to press its case for either his compassionate release or his transfer to a Libyan jail.

The British government did this, the report finds, because it believed that important national interests were at stake. The Libyans attached an “extremely high priority” to Mr Megrahi's return. In particular, commercial interests and co-operation on security issues hung in the balance. Relations with the Libyan ruler, Muammar Qaddafi, had thawed after he agreed to abandon his pursuit of weapons of mass destruction in 2003. Britain was eager to enhance the relationship.

David Cameron, the current prime minister, was tellingly restrained in his response to the report. He said facilitating Mr Megrahi's release was “profoundly wrong”, but stopped short of an all-out condemnation of Mr Brown's behaviour and rejected the case for a further inquiry. Perhaps he knows that any government might have been tempted to help the Libyans. He was a vociferous critic of the decision in 2009, but he has already been in power long enough to know that principles do not always survive contact with the cold realities of government.