In a two-part interview broadcast this weekend, Elton said they had a "whirlwind romance" of love, friendship and music.
Speaking to John's son and his godson Sean Ono Lennon, 44, Elton gushed: "That was the kind of wonderful two or three year whirlwind romance we had and it was such such an important thing in my life, Sean, and it just really helped me."
Elton's riotous and sometimes fractious friendships with Freddie Mercury and Rod Stewart are well-documented but it is extraordinary to hear him describe a far less well-known (and short-lived)relationship with the former Beatle. He told Sean Lennon: "That was the kind of wonderful two or three year whirlwind romance we had, and it was such an important thing in my life, Sean, and it just really helped me. It gave me so much confidence. Your dad was as kind and as generous and sweet and we just hit it off immediately."
The duo met in person for the first time in 1973, and Elton was thrilled to meet one of his heroes.
Sean revealed that the feeling was mutual as he told Elton: "My dad, when he first heard your voice he was in America I think already, and he was thinking that's the first new kind of British singing that he really liked and dug. I think he said that he loved your music and the songs and he liked the song, Your Song."
We laughed so much because we talked about the 50s and 60s and where we grew up, you know, Round the Horne in England, the radio shows we liked, the songs we liked, we didn't like, and your dad was just a fountain of knowledge. It was a hand in glove thing and I never thought that would ever happen.
There was no attitude. I hate posers and I hate attitude and your dad didn't have any of it."
The stars had a close friendship over the next two years, and Elton even played on John's fifth album, Wall & Bridges on his track Whatever Gets You Thru The Night.
Lennon also starred alongside Elton at his iconic Madison Square Garden concert in November 1974.
