LONDON, Nov 1 (Reuters) A copy of a top-secret diplomatic cable found on the counter of a London bank 40 years ago has shed light on the collapse of British efforts to negotiate an early end to the Vietnam War.
The four-page cable, from Prime Minister Harold Wilson to US President Lyndon Johnson, describes Wilson's private meetings with the Soviet foreign minister in February 1967, when London and Moscow were trying to act as a conduit for US proposals to halt the bombing of North Vietnam.
A yellowing copy of the cable was in a file declassified by Britain's National Archive on Thursday.
Murray MacLehose, principal private secretary to Foreign Secretary George Brown, left the copy of the cable at the bank a week after a visit by Soviet Foreign Minister Yuri Kosygin.
Another British diplomat found it and turned it in.
One official described the incident as ''obviously a very grave security breach''. But the file shows Wilson and Brown stepped in to prevent an outside investigation.
''(Brown) wished me to inform the Prime Minister that Mr.
MacLehose was 'a hell of a good fellow'. He had been working extremely long hours with little sleep and had had the misfortune to leave this paper in the Bank of Scotland,'' one official records.
Later in the year, MacLehose was made Britain's ambassador to Vietnam. He would go on to become governor of Britain's colony of Hong Kong.
During Kosygin's visit, Wilson initially passed along what he thought was a US offer to suspend the bombing of communist North Vietnam if the north promised it would then stop sending guerrillas into the pro-American south.
But US officials later insisted they wanted the North to halt the infiltrations first, before they would stop the bombing. British officials were forced to rush to a train station to deliver a revised proposal to Kosygin.
The Vietnamese rejected that proposal. The war continued, and biographers have described the event as a blow to Wilson and a setback in US-British relations.
In the secret cable, Wilson wrote to Johnson of the domestic political pressure he faced over the US bombing. He said he supported US conditions for ending the bombing and would dismiss any proposal from Kosygin that did not include them.
But he also said he hoped Kosygin would offer a counter-proposal ''which could, if successful, lead to a consummation of our efforts to get an honourable set of terms for ending the bombing, infiltration, etc.'' ''I don't want to be in the position of rejecting (all of Kosygin's proposals) and giving him a propaganda victory,'' Wilson wrote.
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