It leaked 30 years ago, but the Glover report on future terrorist trends in Northern Ireland was officially released this week. The history of the 19-page document is a case study in the absurdity of Britain and Ireland's restrictive 30-year rule on the publication of government papers.
It painted a gloomy picture and provided propaganda for the Provos for years to come. Its conclusion was that their campaign would continue until British withdrawal.
"Even if peace is restored the motivation for politically inspired violence will remain. Arms will be readily available and there will be many who are willing and able to use them," the Brigadier concluded - an assessment that would not look out of place in a Real IRA statement today.
The secret assessment was written by Brigadier James Glover, a senior Military Intelligence officer, in 1978. It was shared with the Irish embassy in London a year later, but only after a copy had been obtained by the Provisional IRA and selectively published in An Phoblacht.
Historians and journalists have drawn on it ever since, but we had to await the release of Irish state papers this year to see the authorised version.
Why did the British Government keep such a hopelessly compromised document under wraps so long?
The most obvious answer was they did it because it could. The IRA already had a copy, so no legitimate security interest was served by withholding it.
It would have been far better to have published it in full and instituted a programme of reform designed to address the difficulties identified by Glover.
That would have sent a message that the Government was not hiding its head in the sand and had policies to deal with the security challenges of the day.
Secrecy is seductive and corrupting to those in power. In this case it allowed them to avoid the political embarrassment which openly discussing security failures would have involved.
The same syndrome lies behind the refusal, even after 30 years, to release papers relating to Sir Anthony Blunt, the Soviet spy within British intelligence. The USSR collapsed in 1991 and Blunt himself died in 1983, so no legitimate interest is served by holding back information about his role.
Just as the IRA knew all about the Glover report, the Russians know all about Blunt and the upper-crust spy ring which he led.
Only the UK taxpayers who footed the bill and whose security was compromised are being kept out of the loop. Some details of British espionage against Tsarist Russia are also withheld as are the identities of two informants in the Easter rising of 1916.
The past is a resource from which we can learn, but we have got to know the facts in order to do so.
Instead of the full account, we are presented with a bowdlerised version, censored to spare the blushes of the authorities. In the meantime, interested parties can put their own spin on history through memoirs, official histories and selective leaks.
We are currently denied papers relating to the murder of Airey Neave, Margaret Thatcher's friend and adviser on Northern Ireland, who was blown up in the House of Commons car park by the INLA in 1979.
Thanks to leaks from Special Branch, we know that Raymond Gilmour, an RUC informant, and another police agent gave details of a man who is believed to have travelled to England to kill Neave. The INLA have also boasted that they had a source in House of Commons and the Angry Brigade, a British anarchist group, is believed to have provided support. Withholding the full facts denies us the lessons of history.
Even where papers are released after 30 years political accountability is undermined by the delay.
With the exception of figures like Gerry Adams and Ian Paisley, most political and civil service careers have ended within three decades.
Jim Callaghan and Jack Lynch, who were respectively the Prime Minister and Taoiseach when 1979 opened, are both long dead and Margaret Thatcher, Callaghan's successor, has retired. Justice delayed is justice denied, and now none of them will have to answer questions for the quality of their decision-making.
Why, for instance, was Lord Mountbatten holidaying each year in Mullaghmore, at the height of the IRA campaign, without a bodyguard?
Why, as the state papers reveal, had Garda surveillance of the boat he used been halted in the very year he was murdered by the IRA? Did nobody foresee that planting a bomb on the boat was the obvious way to assassinate him?
The politicians and security chiefs who misjudged the situation are not around to answer these questions.
There are good reasons for withholding some information for a reasonable period of time. The papers reveal that British soldiers guarding the Maze were not allowed fire on escaping prisoners.
Like the statues of soldiers aiming cannons and muskets from the battlements of Carrickfergus castle, the military guards looked impressive, but could do nothing. In retrospect it was probably a good idea to keep this quiet. The guards retained a scarecrow effect to deter escape attempts.
That argument applied while the Maze was still in operation, but the prison closed 10 years ago.
Last January a British Government appointed inquiry recommended that the 30-year threshold before documents can be released should gradually reduce to 15.
It was a cautious enough approach from a committee which included Sir Joe Pilling, Permanent Under Secretary to the Northern Ireland Office from 1997 to 2005. It was welcomed by the Government at the time, but remains a dead letter.
The case can be made for a shorter period, say the life of a parliament, with limited exceptions available where it can be demonstrated that publication would be against the public interest.
Here in Northern Ireland the Stormont Executive is deadlocked on many issues. It might focus the minds of our politicians if they knew that their decision-making processes would be exposed to public scrutiny before their political careers had ended.