Sir Humphrey Appleby is alive and well and exercising in fact his hilariously fictive Yes, Minister occupation of keeping Government Ministers in the dark while he gets on with the job of running the country. That, or the child-like innocence of senior civil servants who did not appreciate the political significance of information that was potentially dynamite, was the only possible reason for the Foreign and Commonwealth Office's failure to take decisive action against a flagrant breach of the United Nations embargo on the sale of arms to war-torn Sierra Leone. That is what the powerful Commons Foreign Affairs Select Committee has concluded in one of the most damning reports ever on the conduct, or misconduct, of government. The report's findings amount to a huge embarrassment for the FCO and its Permanent Under-Secretary, Sir John Kerr.

Pretensions still to run the world? On this evidence they couldn't run a menagerie. It is all very well for the Prime Minister and the Foreign Secretary to go on about the report finding no evidence of a Ministerial cover-up or conspiracy in the arms-to-Africa affair. That is true. So is the fact that many of its findings and recommendations were in the earlier Legg report into the matter. But the crucial difference, as committee chairman (and Labour MP) Donald Anderson clearly implied, is that the committee report carries much more authority and credibility than its predecessor. Sir Thomas Legg is an establishment figure, a retired mandarin whose inquiry was held in secret. The cross-party Parliamentarians, responsible to their fellow MPs and the public at large, carried out their work in public.

It was no easy task, as their report makes clear. Mr Robin Cook exhibited the arrogance for which he is renowned in his obduracy over co-operating with the inquiry while Legg's internal investigation was under way and the handing over of sensitive documents and mat-erial to the committee. The great subtext in all of this is the connected, key issue of governance and scrutiny. It might help explain the startling vehemence of the report's conclusions, and its devastating criticisms of Sir John and the way the Foreign Office was run. It is difficult to disagree with Mr Anderson when he complains about the Government wrongly and unfairly setting up a separate, private, investigation whose purpose, judging from the stink coming from it, was to sideline the powerful committee so much that it disappeared off the horizon.

If that was the intention, it properly failed. Perhaps the most telling part of the report (surely aimed at Downing Street and the Foreign Secretary) emphasises the message that the committee would pursue objectively and vigorously future cases of poor administration in the Foreign Office. Rightly, it points out: ''It is certainly one of the principal justifications for the departmental select committee system: officials and Ministers are aware that the beam of the select committee searchlight may one day swing in their direction, and that they may have to justify their action - or inaction - when subject to the intense scrutiny by a committee such as ours, acting on behalf of Parliament and, beyond that, on behalf of a wider public.'' The report has highlighted the fact that, as far as Sandline and the sale of arms to the former ruling junta's opponents was concerned, the left hand did not

know what the right was doing.

And when it did, it did not seem to know on what terms (even though there were no terms because the embargo applied to all sides in the conflict, knowledge of which the minority dissidents in the committee believe the Sierra Leone High Commissioner, Peter Penfold, was, amazingly, unaware). Even when it was apparent that the embargo was being breached weeks elapsed before Mr Cook was told. This is the very Foreign Secretary who, in his first days in the job, signed the Foreign Office up to a ''mission statement'' founded on an ''ethical'' foreign policy. Yet alarm bells did not seem to ring among senior civil servants when news of a distinctly unethical breach of an international arms embargo started to come out. It really is time to drop a policy rendered indefensible, and utterly discredited by the Sand-line affair and the sale of arms to Indonesia.