Off duty on that same Friday the 13th, and waiting to meet his wife for some Christmas shopping, Detective Constable James Morrison, 26, spotted a pickpocket at work in Montreal Place in the Aldwych, central London, and gave chase. He caught the man, who fought back viciously.

“I’m a policeman,” Morrison shouted. Undeterred the pickpocket produced a knife and stabbed the detective. Morrison died shortly after admission to hospital.

The killer was described as “a well-dressed Arab” and during their investigations police uncovered a huge illegal operation involving bogus Algerian asylum seekers. Some 300 Algerians were interviewed, half of them involved in petty crime. Detective Morrison, who was killed on Friday, December 13th, 1991, was one of four policemen murdered while on duty in England in 1991.