Archived internal BBC documents from the 1980's, obtained by The Sunday Telegraph under Freedom of Information legislation, reveal that the British spy service, MI5, was used to vet existing and potential staff at the public broadcaster. The paper reported that the documents revealed that "at one stage it [MI5] was responsible for vetting 6300 BBC posts - almost a third of the total workforce." The BBC adopted "categorical denial" as its "defensive strategy" to deflect questions about the practice by unions. A March 1, 1985 memo suggested the best approach was "keep head down and stonewall all questions."