London — Clive Ponting, a senior civil servant in Britain's Defense Ministry, is not your ordinary informer. His work in saving the ministry more than (STR)5 million ($6.5 million) in naval service costs a few years ago was well enough known and acknowledged to win him an Order of the British Empire.
Not a faceless bureaucrat, he is personally known to Prime Minister Margaret Thatcher.
Now, in an ironic twist, the man who until earlier this year headed the Defense Ministry's legal division, which handles Official Secrets Act cases, is himself to be prosecuted under the same act. He is scheduled to stand trial on Oct. 9.
Unlike some informers, who are shunned for leaking information, this official is receiving a fair measure of support and sympathy for divulging information that points to apparent inconsistencies in the government's account of the Falk-lands war in 1982.
Specifically, Dr. David Owen, leader of the Social Democratic Party, has urged that he should not be prosecuted.
Neverthless, Mr. Ponting's disclosures were bound to be controversial.
Prime Minister Thatcher carried much of the country along with her in insisting that it was a matter of principle that Britain retake by force the Argentine-occupied Falkland Islands, which are a British possession.
Public opinion remains largely sympathetic to the view that varying versions of what happened during the Falklands war can be put down to the vast distances involved and that a time of war produces different criteria.
Yet the Ponting disclosures are both embarrassing and disturbing to the Thatcher government.
Embarrassing because they have aroused suspicions that in some of its pronouncements the government did not tell Parliament the truth.
Disturbing, because Ponting's action in anonymously handing over two Defense Ministry documents to Tam Dalyell, a Labour member of Parliament, is one of a series of information leaks the government feel have reached epidemic proportions. The government is worried that such disclosures by a variety of people undermine the workings of the state.
Earlier this year, Sarah Tisdall, a Foreign Office informer, was imprisoned under the Official Secrets Act after a high court ordered the Guardian newspaper to return secret documents about the cruise missile.
The Ponting disclosures raise critical questions about the responsibilities of ministers and civil servants in public life.
Where, for instance, do a civil servant's loyalties lie? To Parliament, which represents the people, or to the ministers he or she serves?
And what happens if a minister deliberately conceals information, which might be in the public interest to know, in order to save himself political embarrassment?
To what extent does a state of war, such as the Falklands, exonerate a minister from the need for full disclosure?
Whatever improprieties Mr. Ponting has been guilty of, his leaks and the consequences of his actions have opened up an agitated debate on the parameters of the law and of the public's right to know.
Senior civil servants have called for a code of ethics that would allow civil servants to refuse to carry out in-structions issued by ministers that involved dishon-esty.
Some have argued against the severity of the Officials Secrets Act, in which divulging information that may not involve national security or endanger people's lives is regarded not as a breach of trust but a criminal action to be prosecuted.
The Ponting leaks have also refueled the debate - with Lord Scarman, the noted British jurist in the forefront - as to whether the British government is not excessively secretive. Lord Scarman has taken the view that there are matters of public debate that should pierce the veil of government secrecy.
Under the Official Secrets Act, which dates back as far as 1911, virtually all official information is secret information. Section 2 of that act makes it an offense for any civil servant to communicate a document or information to an unauthorized person.
An ''unauthorized'' person can be a member of Parliament - as it was in this case when the two documents in question were handed over to Mr. Dalyell, Labour MP for the Scottish constituency of Linlithgow.
Mr. Dalyell's efforts at publicizing their contents brought demands on the Thatcher government to produce a white paper or call a public inquiry. Mrs. Thatcher has refused but has allowed Defense Minister Michael Heseltine, who was not minister at the time of the Falklands war, to appear before the Select Committee on Foreign Affairs.
What the documents purport to show is that the government's rationale for attacking the Argentine cruiser Belgrano, which went down with 368 lives May 2, 1982, is at odds with the facts.
The government has insisted that the Belgrano was sunk because it was approaching the British naval task force, and, as such, posed a potential threat.
The documents allegedly make two damaging claims:
1. That the government knew the cruiser was heading home, and therefore moving away from the fleet, 11 hours before it was sunk.
2. That information about changes in the rules of engagement during the Falklands war - which freed British submarines to sink the Belgrano - was withheld from Parliament. Those changes were not officially conveyed to Argentina until five days after they were announced.
The changes were announced by the government at 1 p.m. on May 2. This allowed British forces to go outside the exclusion zone. The rules were conveyed to the submarine Conqueror at 2 p.m. and repeated at 4 p.m. and again at 6 p.m. At 8 p.m. Conqueror sank the Belgrano.
British officials claim that the Belgrano, irrespective of its position, remained a threat to the British naval task force. As an official put it, ''It was not on a pleasure cruise.''
(Yesterday, Mrs. Thatcher said the Cabinet had not been informed of the Belgrano's change in position. Even if it had, she said, it would not have made any difference.)
The changes in the rules of engagement, clearing the way for the attack on the Belgrano, have been cited as evidence of Britain's intention to wreck Peruvian peace proposals.
Admiral Lord Lewin, a member of the War Cabinet, insists not only that the Cabinet was unaware of those peace proposals at the time the Belgrano was attacked, but also that it wouldn't have made any difference if his Cabinet colleagues had known.
What Lord Lewin is saying is that the British had no faith in the Argentines reaching a negotiated settlement anyway. Two years after the Falklands war Whitehall takes the view, analogous to the bombing of Hiroshima in World War II, that the sinking of the Belgrano hastened the end of the war by keeping the Argentine fleet tied up in port.
Some British commentators critical of apparent inconsistencies in government explanations have argued that the issue is not whether the Belgrano should have been sunk, but that the government should have told the truth.
The domestic row over the Falklands will not materially affect the future course of Anglo-Argentine relations. Talks to bring about a normalization of ties have foundered on the single issue of sovereignty of the Falklands.
Britain is willing to have an open agenda in which peripheral topics can be discussed to smooth the way for the more intractable problems. But Argentine insistence on adhering to sovereignty as the raison d'etre for discussion makes any future talks a nonstarter in British eyes.