Thatcher presses point of principle: official secrets should be kept. But press accounts of spy memoirs make it harder to keep lid on

The government of British Prime Minister Margaret Thatcher has decided to prosecute three newspapers for publishing details from a book by a former spycatcher who claims British security services in the 1970s plotted to overthrow former Labour Prime Minister Harold Wilson. The accusations are contained in a book of memoirs by Peter Wright, a former senior officer of MI5, Britain's domestic counterintelligence agency. Mr. Wright now lives in Australia and Mrs. Thatcher is trying to prevent the book's publication in that country on the grounds that it would damage British security arrangements.

On April 27, London's newest ``quality'' newspaper, the Independent, defied a court ban when it reported Wright's book describes a plot by 30 MI5 officers to destabilize the government of Mr. (now Lord) Wilson in 1974. The Independent, which that day ran three page-one articles on the memoirs, claimed that its stories were based on an unsolicited copy of the unpublished Wright manuscript. Two other London papers, the Daily News and the Evening Standard, followed suit by publishing details from the memoirs. This led the government to launch contempt-of-court proceedings against all three papers.

The book alleges that the MI5 attempted to destabilize the government by spreading rumors that Wilson, who served as prime minister between 1964 and 1976, was a security risk because of his close relations with the Soviet Union.

The Independent's reports pressured Thatcher into making a House of Commons statement. But she limited herself to telling Parliament that an inquiry instituted by Wilson's successor, former Labour Prime Minister James Callaghan, had not supported suggestions that there had been an MI5 plot.

No matter what the outcome of the government's plan to prosecute the Independent and hold up publication of Wright's book, it seems likely that pressures for a fuller disclosure by Thatcher will continue to build.

Labour Party supporters have described the alleged MI5 plot as ``treason.'' Roy Jenkins, Labour home secretary in 1974, and Merlyn Rees, his successor, have both called for inquiries. David Owen, leader of the Social Democratic Party and a former Labour foreign secretary, believes a full disclosure by the government is imperative.

Wright's memoirs are said to be an ``insider's view'' of the secret operations of the security services, which have in the past few decades been plagued by allegations (some authenticated) of homosexual conduct and spying for the Soviet Union.

Peter Hennessy, a leading authority on the British constitution, says the alleged Wright allegations raise deeply serious political and constitutional questions. ``Only a political society and a public life that has become so jaded as to be unshockable could fail to see in the Wright allegations prima facie evidence'' of rot at the secret core of British government, he says.

Under British law, civil servants (including security agents) are responsible to their departmental head, who in turn is responsible to a minister of the crown. Ministers answer to Parliament. On this basis, an MI5 plot against a prime minister would be treasonable activity.

The pressures generated by the Independent reports are likely to make it harder for the government to continue with its attempts to block publication of the Wright memoirs. The most important Wright revelations may have already been published, so there may be little point in Thatcher's trying to prevent the book from appearing.

On the other hand, the British government has always argued that it was insisting on a point of principle: that an MI5 officer who, like Wright, had signed the Official Secrets Act should not be allowed to publish memoirs in which secrets are revealed. Thatcher may decide that this principle is more important than the revelations in Wright's book.

The timing of the reports is sensitive for Thatcher, who may be about to enter a general election campaign. She does not want the allegations to snowball into an election issue for the Labour Party, which might find it impossible to avoid insisting on full disclosure of a plot against a former Labour prime minister.