Those first four notes of its theme tune were instantly recognised and announced the start of perhaps the most famous police procedural in history. Set in Los Angeles and headed by police detective Sergeant Joe Friday the show has influenced all the many others that have followed in its illustrious footsteps.

It was based on real cases from police files. It described the methods used to track down the culprits and its technical language added to its authenticity. It was a ratings hit year in, year out.

Played and produced by Jack Webb its pared-down acting brought both the dull routine work and its acts of heroism and unselfishness into the living rooms of ordinary Americans, explaining a side of society that they only read about in the papers, heard in news bulletins or saw fabricated at the movies.

It's time for the truth and for Sergeant Joe Friday to set the record straight.