Elton was speaking on the first of BBC Radio 2's two-part 'John Lennon At 80' specials.
The hour-long 'John Lennon At 80' programs will be broadcast on October 3 and 4.
The film documents the couple's unique and enduring relationship and the creation of the 1971 album 'Imagine.'
The picture disc 7” which perfectly replicates the track artwork and the CD single edition comes with heavyweight packaging.
The documentary’s includes interviews with Yoko Ono, Julian Lennon and photographer David Bailey among other notables.
Billed as “the untold story” of John Lennon's 'Imagine', the documentary also explores how Lennon and Ono's art, politics and music were intrinsically entwined.
Julian Lennon’s White Feather Foundation will establish the Cynthia Lennon Scholarship For Girls, in honour of Julian’s late mother.