Songfacts®:

• This song is an example of the "noir thing" Costello says runs through much of his material. Inspired by American detective shows, the lyric is filled with images of detective, dames, guns and cigarettes - all the film noir tropes. The story is rather opaque, but the wordplay is quite compelling.
• Elvis Costello wrote "Watching the Detectives" after an all-night bout of listening to The Clash's debut album, The Clash, on headphones, which explains the reggae influence. Fortified by drinking an entire jar of instant coffee, he stayed awake for 36 hours. Costello told Q magazine August 2013: "Why do you think that song is so jerky? I drank a lot of coffee."
• Costello justifies his later performance of this song as a big-band number, saying that it should be realized as an orchestral piece using the film music feeling and the swing rhythms of 1950s detective shows.
• This song had different B-sides on the single release; in the UK, two live tracks of "Blame it on Cain" and "Mystery Dance," and in the US, the song "Alison," the lead track from Costello's second single.
• Covers of this song include Duran Duran in 1995 on their Thank You album, Jenna Mammina in 1999 on her Under the Influence album, and Toto in 2002 on their Through the Looking Glass album.
• Even though "Watching the Detectives" is credited to "Elvis Costello & the Attractions," this song's lead track was actually recorded in May of 1977, before the Attractions formed. The backing was Steve Goulding on drums and Andrew Bodnar on bass guitar, both from Graham Parker's band, The Rumour.
• The keyboard overdubs were added later by regular Elvis Costello collaborator Steve Nieve. The singer had in mind a piano sound that utilised the sort of short repeating patterns that movie composer Bernard Hermann was renowned for. Costello recalled to Billboard:
  
  "When we did 'Watching the Detectives,' it was the first record that Steve Nieve played on. He was 19, straight out of the Royal College, and we'd only just met. I said, 'This is about detectives, I want a piano thing that sounds like Bernard Hermann,' and, of course, he didn't know what I'm talking about, so I go [makes staccato, sharp sound], and what you hear on the record is this galloping piano thing that rushes the beat and it sounds like one of those sudden jarring gestures that Hermann would use a lot. But we didn't have 19 clarinets or whatever he used [in] Torn Curtain; we just had a battered upright in an eight-track studio. What you imagine you have to render whether you use a fuzz-tone guitar or a symphony orchestra and everything in between."
• This inspired the UK ska band Madness' 1979 hit "My Girl."