Ancram's office has also questioned how thorough the Foreign Office investigations were, given that several of the alleged plotters were either British citizens or lived in Britain.
Mann's company, Logo Logistics, was registered in Guernsey and he was well known to the circle of former British military men who run private security firms.
In addition, Mann is alleged to have meetings in London, with millionaire oil trader Ely Calil. Both men deny involvement in the plot. On Friday, Thatcher will face trial in South Africa.