"I Won't Let the Sun Go Down on Me" only reached number 47 in the UK charts when first released. However, the follow-up single from the same album, "Wouldn't It Be Good", reached the top five and on the back of that success "I Won't Let the Sun Go Down on Me" was re-released and soared to number two. It was also subsequently a major hit in several other countries and was responsible for bringing Kershaw to greater public attention. During an appearance on BBC One's The One Show in June 2015, Pete Waterman claimed he produced the record. Kershaw took to social media to point out that "I Won't Let the Sun Go Down on Me" was in fact produced by Peter Collins, who is credited on all releases as the record's sole producer. (Waterman managed Collins at the time the song was recorded, but had no involvement in the actual production of the track.)

The song was written during the latter part of the Cold War period when nuclear war between the two superpowers of the USSR and United States was still a very real concern, and the lyrics reflect a satirical view of politics and the threat of war with lines such as: "old men in stripey trousers, rule the world with plastic smiles", and: "forefinger on the button, is he blue or is he red?"

In September 1984, Kershaw told "Number One" magazine:

It's probably not immediately obvious but I Won't Let The Sun is about The Bomb, or rather about people taking responsibility for what they do generally. It's saying that it probably won't do much good for one person to shout about these things but I'm going to anyway.

The song was originally written as a folk protest song, but as Kershaw's manager had signed him up to Peter Collins and Pete Waterman's Loose Ends production company, it turned into a pop anthem in the studio.

In Kershaw's version, the synth tune was produced with an Oberheim OB-8 played by Paul Wickens (Wix).

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