Songfacts®:

• When Buzzcocks played their first concert, Steve Diggle was their bassist, but founding frontman Howard Devoto's departure prompted the band to reshuffle, with Pete Shelley becoming lead vocalist/guitarist and Diggle moving from bass to guitar and co-vocalist.
  
  Diggle also had a few early co-writing credits and contributed chords and choruses to "Promises" shortly after Pete Shelley's "Ever Fallen In Love (With Someone You Shouldn't've)." "Harmony In My Head," which reached #32 in the UK, is probably Diggle's best known song.
• Diggle told Uncut magazine in 2021 the song was inspired by walking around Manchester's newly built Arndale Centre - one of the first "American style" malls built in the United Kingdom.
  
  "I was reading James Joyce's Ulysses, which is a heavy book," he said. "But it had a lot of cinematic imagery – so 'Harmony' wasn't a linear story like pop songs are. The Arndale Centre had just been built and it gave me a real sense of alienation. I wanted to walk down the street and hear the percolation of the crowds – that was the 'harmony.' Life was never going to be sweet and nice and it's not always doom and gloom. The 'Harmony In My Head' was the sound of the crowd. That's how real life is."
• Diggle smoked 20 cigarettes to get the gruff sound of the vocals. Engineer Alan Winstanley recalled to Uncut: "'Harmony' is interesting as it's the only one Steve Diggle sings - it doesn't have that Pete Shelley sweetness - but when he comes in on the chorus it really changes it. Then off Steve goes again with his growly voice."
• Released as a standalone single on July 13, 1979, the song spent six weeks on the UK singles chart, peaking at #32.