The government cited Rotberg's failure to seek pre-publication approval as the reason for declaring his book prohibited material and declaring the author a prohibited immigrant. Most of the foreign researchers, who did not have enough time to wait until the minister was free to grant them an interview, abandoned their research plans or looked elsewhere for sources. In Malawi, between 1951 and 1964, archival material in the national archives could be utilised by diverse researchers because the government did not impose restrictions on consulting open public records. During the Malawi Congress Party's annual convention in March 1967, the government declared the Watchtower Movement, or Jehovah's Witnesses, a prohibited religious movement in Malawi. In September 1966, Mr L. J. L. Nthenda, a Malawian doctoral student at the University of Oxford researching the administration of central government in Malawi from 1920 to 1955, was granted permission to consult the archives by the president.