Songfacts®:

• This song is a tribute to Spice Girls member Geri Halliwell, who's close friends with Robbie Williams. He wrote it after the pair holidayed together in France in the summer of 2000. Williams later called it "the most amazing summer."
  
  The pair grew close after Halliwell quit Spice Girls in 1998 in a similar fashion to Williams leaving Take That in 1995. Halliwell has since credited Williams for helping her overcome the bulimia she was suffering from at the time, telling Piers Morgan's Life Stories in April 2010: "When I was really struggling with an eating disorder, he pointed me in the right direction of how to sort it out. He told me to go to a 12-step program. It saved my life. I'm incredibly grateful to him."
• Brian May of Queen plays guitar on this song. Williams, May, and Roger Taylor also came together to record a new version of "We Are the Champions" for the 2001 Heath Ledger movie A Knight's Tale. Williams claims he subsequently turned down an offer from May and Taylor to front Queen. He told SiriusXM in March 2020: "I just thought I'd save them the audacity of me even trying to step on a stage and be in the same echelon as Freddie Mercury. He, to me, is angelic. He's godlike. It was just too scary."
• The music video for "Eternity" serves as a sequel to the video for "The Road To Mandalay," which depicts Williams and his criminal associates robbing an armored vehicle carrying loads of cash. "Eternity" sees Williams relaxing with his on-screen girlfriend, Australian model Lisa Seiffert, in his hilltop mansion in the aftermath of the heist. The Vaughan Arnell-directed video then concludes with Williams getting arrested after forensic police manage to track him down from clues left at the crime scene.
• A comedic version of "Eternity" can be heard in "Outtakes," a hidden song on Williams' swing covers album Swing When You're Winning. An orchestral version was also issued as a B-side to Williams and Nicole Kidman's cover of "Somethin' Stupid" by Nancy Sinatra and Frank Sinatra.
• "Eternity" was released as a double A-side alongside "The Road to Mandalay." Unlike "The Road to Mandalay," "Eternity" doesn't appear on Williams' third album Sing When You're Winning, although it was eventually included on Williams' Greatest Hits compilation. "Eternity"/"The Road to Mandalay" was Williams fourth #1 in the UK after "Millennium," "She's the One"/"It's Only Us," and "Rock DJ."
• During his 2023 Netflix titular documentary, Robbie Williams said he began dating Geri Halliwell while he was going to Alcoholics Anonymous. He added that he loved spending time with the former Spice Girl: "I just found her company very, very easy. There was a silliness. We really got on really well. It was fun."
  
  They broke up after a few months, reportedly because of the pressure of their celebrity lifestyles. "Wherever we went, the paparazzi were there before we got there," said Robbie. "These very private personal moments became public property and we were just dumbfounded how this could be happening."
  
  Despite their short-lived romantic relationship, Williams and Halliwell have remained friends.