Germany's most notorious postwar neo-Nazi party was led by an intelligence agent working for the British, according to both published and unpublished German sources.
The alleged agent - the late Adolf von Thadden - came closer than anyone to giving the far-right real influence over postwar German politics.
Under his leadership, the National Democratic party (NPD) made a string of impressive showings in regional elections in the late 60s, and there were widespread fears that it would gain representation in the federal parliament.
Yet, according to a report earlier this year in the Cologne daily, the Kölner Stadt-Anzeiger, the man dubbed "the New Führer" was working for British intelligence throughout the four years he led the NPD, from 1967 to 1971.
However, a former senior officer in German intelligence told the Guardian this week that he had been informed of a much longer-standing link between Von Thadden and British intelligence. His recollection raises the question of whether the German far-right-winger was under the sway of M16 when he and others founded the NPD in 1964.
Dr Hans Josef Horchem, who was the head of the Hamburg office of the Verfassungsschutz - the West German security service - from 1969 to 1981, said he received regular visits from British intelligence liaison officers.
"We held general discussions on security. At one of these - I think it was towards the end of the 70s- they said, 'Adolf von Thadden was in contact with us', and that that was in the 1950s". Mr Horchem did not know whether the links between the German and British intelligence had continued into the 60s and 70s.
According to the Kölner Stadt-Anzeiger, whose report passed virtually unnoticed when it was published, the neo-Nazi leader met his British contact at a hotel in Hamburg.
Germany's government is currently trying to ban the NPD on the basis that its policies violate the constitution.
But the government's case is in danger of collapse after the disclosure that some senior NPD members were agents of the Verfassungsschutz. This has sparked debate about the extent to which counter-intelligence officers were sustaining the far right in their efforts to monitor it. Similar issues arise in Von Thadden's case.
The question also arises of whether MI6 was seeking help from the neo-Nazi movement when far-left militancy was sweeping Europe after the uprising of May 1968 in Paris.
Von Thadden left the NPD in 1975, and died at the age of 75 in 1996.
His younger sister, Barbara Fox von Thadden, said she had had no reason to suspect her brother worked for British intelligence. But she added that they had very different political views and steered away from political discussion.
They had an English grandmother, and Ms Fox von Thadden said her brother "did like coming to Britain, and did like Britain very much". http://www.guardian.co.uk/world/2002/aug/13/johnhooper