It was supposed to be Scotland’s publishing event of the year, former justice secretary Kenny MacAskill’s long awaited account of his controversial decision to release the convicted Lockerbie bomber Abdelbaset al-Megrahi.

Serialised in the Murdoch press and endorsed by former First Minister Alex Salmond, ‘The Lockerbie Bombing’ looked set to enhance the reputations of MacAskill and the criminal justice system he served.

In the event, the book has made an even bigger splash than expected, but not in the way that he intended. By the time it was published last week, it had plunged the Megrahi case into chaos and left MacAskill looking rattled, if not a little foolish.

The book gives the inside track on the grubby international power play that surrounded his decision to allow the terminally ill Libyan to return home. But it goes much further, answering, according to its dust jacket, “how and why [the bombing] happened – and who was really responsible”. It is here, in his efforts to play sleuth, judge and jury, that MacAskill has come unstuck.

He argues that Megrahi was guilty – a significant player in a much larger plot. One of the book’s few genuine revelations, however, details a secret document which implicates the terror group the Popular Front for the Liberation of Palestine-General Command (PFLP-GC) in the Lockerbie bombing carried out on December 21 1988.

MacAskill in his book identifies who sent the document and who received it - an act strictly forbidden by the law. As the Sunday Herald revealed last week, in publishing such details, MacAskill was in breach of a Whitehall gagging order and very likely, at least in the opinion of the Foreign Office, of the Official Secrets Act. The former Scottish Justice Secretary later admitted that he was ‘unsure’ whether he had broken the act.

MacAskill downplays the letter’s significance, claiming it was sent soon after Lockerbie, and before evidence had emerged to implicate Libya and Megrahi. This is one of the book’s many factual errors. At Megrahi’s second appeal it was revealed that the UK government had seen the letter in September 1996, five years after it had claimed that Lockerbie was a ‘Libyan operation from start to finish’.

Overshadowing these revelations, however, is a single sentence buried among the book’s 322 pages, which reads: “Clothes in the suitcase that carried the bomb were acquired in Malta, though not by Megrahi.”

Its significance rests on the reasoning of the three Law Lords who convicted Megrahi. They concluded that he had sent a bomb concealed within a suitcase on Air Malta flight KM180 from Malta to Frankfurt and that it was later transferred to Pan Am flight PA103 at Heathrow. The case was largely circumstantial, with only two points that directly incriminated Megrahi in the bombing. One was his presence at Malta’s Luqa airport when KM180 was loading and the other was the testimony of Maltese shopkeeper Tony Gauci that he resembled the man who bought the clothes packed in the suitcase.

The judgment was clear that the failure to explain how Megrahi had got the bomb on to KM180 was ‘a major difficulty for the Crown case’, however, it accepted that when taken together with other evidence – crucially Gauci’s – the inference that the bomb came from Malta was ‘irresistible.’ 

The most important link in the Crown case, Gauci’s evidence was also the weakest.

The clothes purchaser he described was much older and bigger than Megrahi and there is persuasive evidence that the purchase took place when Megrahi was not in Malta.

As the Scottish Criminal Cases Review Commission noted when it referred Megrahi’s conviction to the appeal court in 2007, the assumption that Megrahi was the clothes purchaser was critical. Without it, there was insufficient evidence to convict him.

By Monday evening MacAskill, had conceded in two TV interviews that Megrahi’s conviction was probably unsafe, a startling volte face, given that the Scottish government, which he served as justice minister, repeatedly stated that it did “not doubt the safety of the conviction.”

His concession was not lost on the Justice for Megrahi (JfM) campaign group, which believes the Libyan was wrongly convicted. By then they had written to Police Scotland’s Operation Sandwood team, which is investigating allegations of criminal misconduct made by JfM against some of the Crown servants responsible for the conviction.

JfM say MacAskill is an important and compellable witness, and that the police must establish the basis for his claim that Megrahi was not the clothes purchaser.

‘The weaknesses in the identification evidence were well known to the Scottish government when MacAskill, as Justice Secretary, was claiming that the conviction was safe,’ says JfM’s Iain McKie, a former police superintendent who spent 15 years battling the police and Crown Office to clear the name of his daughter Shirley McKie.

‘So what does Kenny know that we don’t that has caused him to change his mind? If any of it was previously secret, then the Crown Office has to explain why it wasn’t disclosed to the defence. Was Mr MacAskill aware of it when as government minister he was declaring the conviction safe and turning down JfM’s petition for an independent public inquiry? Was he in any way misleading or deceiving the Scottish Parliament and the Scottish people?’

There is a still more important question: is MacAskill saying publicly what the Crown is saying privately? ‘The book reads,’ says McKie, ‘as if the Megrahi-wasn’t-the-clothes-purchaser-but-was-guilty-anyway line has been fed to him.

“If it was the Crown doing that, then the consequences are immense, because they have a duty to report that to the court, in which case the conviction falls.’

Publicly the Crown Office is sticking to the line that Megrahi’s conviction is safe, but it must be dismayed by MacAskill’s statements, not least, his barely veiled criticism of the secret $2 million reward payment made to Gauci, which the Crown Office tacitly sanctioned.  

MacAskill continues to insist that Megrahi was guilty, but his case is built largely on untested evidence and assertions, and he has sidestepped important exculpatory evidence that has emerged since Megrahi’s conviction. All rather surprising for a former defence lawyer.

This flags another intriguing question: how, given his legal background, could MacAskill have landed himself in such a mess? Did he not realise that revealing details of the document subject to a Whitehall gagging order might be illegal? And did he not foresee the consequences of conceding that Megrahi was not the clothes purchaser?

His book’s subtitle is ‘The Search for Justice’. Ironically, its unintended consequence may be to help achieve justice for Megrahi. 

John Ashton is the author of ‘Megrahi: You are my Jury’ pub. Birlinn, 2011) and ‘Scotland’s Shame: Why Lockerbie Still Matters’ (Birlinn, 2013). From 2006 to 2009 he worked with Abdelbaset al-Megrahi’s legal team.