The song continued to appear in critics’ selections of the greatest recordings. Rolling Stone ranked it at number 57 on The 500 Greatest Songs of All Time. Musicians also embraced the work extensively, with various artists performing more than 1,000 cover versions.

The original songwriting attribution named two members of Procol Harum. Brooker received the music credit, and Keith Reid was credited as lyricist. Their bandmate Matthew Fisher later pursued recognition for his contribution to the composition. In 2009, his court action succeeded, giving him a co-writing credit for the music.

In an interview with Uncut Magazine, Reid said his objective was as much to establish a mood as to relate a direct story about a girl leaving a boy. Images involving a vanishing ceiling and an increasingly humming room were meant to create an evocative scene. According to Reid, he was not deliberately trying to make those details mysterious.

Reid also addressed the seemingly decadent circumstances depicted in the lyrics. He said he had been too young at the time to possess any personal experience of decadence. While he thought he might have been smoking when the idea occurred to him, he said that was not the case while he actually wrote it. He credited books, rather than drugs, with influencing the song.