Secret papers: Alliances and arms deals show flexible morality

According to Labour Foreign Secretary George Brown in 1967, it was not "morally acceptable" to condemn the Americans over their involvement in Vietnam. It was, however, morally acceptable to use the Royal Air Force secretly to deliver ammunition to the Israelis on the eve of the Six Day War and to make careful calibrations of the kind of weaponry it was acceptable to supply to the Nigerian military junta for use in the bloody suppression of a revolt by its eastern region, or Biafra as it became known to the world.

The papers demonstrate the then Prime Minister Harold Wilson's pro-Israeli sympathies. Arms deliveries took place from British airfields - RAF Waddington was used by Israeli aircraft to fly out ammunition and shipments left ports at night in sealed cargo vessels.

At the same time, the Cabinet was drawing up contingency plans for petrol rationing in the event of an oil embargo by the Arab states. Ministers even suggested that the oil companies, such as ICI, might try to obtain petrol from the Soviet Union.

In the event the petrol supply, particularly from Iraq, was cut but the crisis passed without full-scale rationing.

The archive contains a personal letter from Harold Wilson to Levi Eshkol, the Israeli Prime Minister. "I am glad we were able to help you, now I am sure you will understand our concern that the utmost secrecy should be maintained. However good the explanation the story could be used with devastating effect in propaganda against both of us."

Oil was at stake in Nigeria, too. At the outset of the revolt by the Biafrans, each side demanded that the British coerce Shell and BP into paying them their royalties. In addition, General Yakubu Gowon, the Federal leader, put a 48-hour deadline for acceptance of his demand for additional military equipment to crush the rebel Biafrans.

The advice for BP and Shell was to delay a decision in payments, to "play it as long as possible, putting off the evil day until the end of July". Chiefs of staff drew up two top-secret evacuation plans, using the carrier HMS Albion to lift 16,000 British nationals out of the war zone.

Wilson delayed sending arms to the federal regime as long as possible, finally dispatching 200 anti-aircraft guns and armed cars to the Lagos government. At one point he instituted an inquiry into whether the United States Central Intelligence Agency were providing weapons for Biafra, asking: "Are we really sure they had nothing to do with it?"

This was a world where - according to George Brown, the Foreign Secretary - the Communists were "mobilising a skilful worldwide propaganda campaign" on Vietnam. To condemn the US, he said in a cabinet memo, is to condemn the major power in the conflict which has publicly proclaimed a policy aimed at securing for the South Vietnamese the right to order their own affairs.

Harold Wilson had proposed a dramatic joint peace mission with Soviet leader, Alexei Kosygin, to end the war. The suggestion, made at an embassy reception in London in February 1967, seemed to have been treated with no more than mild amusement by the Russian leader. Picking up a fork, Kosygin told Wilson: "If one took a piece of metal and attempted to make a fork without knowhow to do so one would spoil the metal without producing a fork".