Bestselling author Stephen King, a huge fan of the series, was especially fond of the Irish catchphrases used by superintendent Ted Hastings (Adrian Dunbar) such as, "Now we're sucking diesel!" (when you've fallen into good fortune thanks to your own hard work) and "Jesus, Mary and Joseph and the wee donkey!"
The police refused to cooperate with the series' producers. Consequently the production team were advised both by retired policemen and anonymous serving officers. They also made use of anonymous police blogs.
The series was the highest-ranked current series in a list of the best cop shows of all time and in a poll of the best British crime dramas of all time.
The show is set in an unidentified British city. Several named settings are fictional. However there are many things throughout the show to suggest that said 'city' is somewhere in the Midlands, most likely Birmingham.
The name of the city is not mentioned. Maps of Birmingham appear on walls and telephone numbers use an 0121 area code, so would indicate Birmingham.