Douglas Adams was a friend of Gary Brooker, the lead singer, pianist and songwriter of the progressive rock band Procol Harum. Adams is known to have invited Brooker to one of the many parties that Adams held at his house. On one such occasion Gary Brooker performed the full (4 verse) version of his hit song "A Whiter Shade of Pale". Brooker also performed at Adams' memorial service.

Adams also appeared on stage with Brooker to perform "In Held Twas in I" at Redhill when the band's lyricist Keith Reid was not available. On several other occasions he had been known to introduce Procol Harum at their gigs.

Adams also let it be known that while writing he would listen to music, and this would occasionally influence his work. On one occasion the title track from the Procol Harum album Grand Hotel was playing when...

Suddenly in the middle of the song there was this huge orchestral climax that came out of nowhere and didn't seem to be about anything. I kept wondering what was this huge thing happening in the background? And I eventually thought ... it sounds as if there ought to be some sort of floorshow going on. Something huge and extraordinary, like, well, like the end of the universe. And so that was where the idea for The Restaurant at the End of the Universe came from.

—Douglas Adams, Procol Harum at The Barbican