Deep Purple's Ian Gillan has said that "Child in Time" is based on It's a Beautiful Day's psychedelic song "Bombay Calling". It's a Beautiful Day in return borrowed Purple's "Wring That Neck" and turned it into "Don and Dewey" on their second album "Marrying Maiden" (1970). As Ian Gillan put it in a 2002 interview, "There are two sides to that song - the musical side and the lyrical side. On the musical side, there used to be this song 'Bombay Calling' by a band called It's A Beautiful Day. It was fresh and original, when Jon was one day playing it on his keyboard. It sounded good, and we thought we'd play around with it, change it a bit and do something new keeping that as a base. But then, I had never heard the original 'Bombay Calling'. So, we created this song using the Cold War as the theme, and wrote the lines 'Sweet child in time, you'll see the line.' That's how the lyrical side came in. Then, Jon had the keyboard parts ready and Ritchie had the guitar parts ready. The song basically reflected the mood of the moment, and that's why it became so popular."