On the 26th November 1980 an anonymous letter was received at the Millgarth incident room. The letter, which was one of many being received at the time, suggested that a man called Peter Sutcliffe was the "Ripper".
The claim was supported by a number of minor points about Sutcliffe’s employment and character, but particular mention was made of an incident which had occurred within the previous five years of which the author of the letter could not give details because they might lead to him being identified.
The author of this letter has since been identified as Trevor Birdsall a close friend of Peter Sutcliffe.
Birdsall’s girl friend, who had urged him to write the letter, later advised him that its contents were insufficient to enable the police to act and persuaded him to report to the police personally. Birdsall accepted this advice and visited Bradford Police Station late on 26th November 1980.
He repeated the suspicions which he had voiced in his letter to Constable Butler and added that he had been to Halifax with Sutcliffe in August 1975 and suspected that Sutcliffe had assaulted a woman on that occasion. Constable Butler submitted a report on Birdsall’s visit to the Millgarth incident room.
By this time the incident room was suffering a progressive collapse because of the weight of information being put into the system and because the number of actions which were generated by new and existing information could not be accommodated by the officers who were available to deal with them. There is little doubt that Constable Butler's report was received in the incident room but efforts to trace it proved unsuccessful.