Sir Elton John's producer found the legendary singer "extremely volatile"

Andrew told People magazine: "[He's] a little more like Beethoven, I would say, and when he's writing, he's extremely volatile."

As a result, the 35-year-old producer tried to work with Elton in a particular way in order to stay out of his firing line.

He said: "My job is to read the room, and if you're in Elton's eye line as he's writing, you're in the f****** lion's den.

"So I would try and be around him to make sure I was close enough to when he would call for me or needs something, or I could hear what he was doing, what he was coming up with.

"[I] would try and be out of his direct eye line."

While Andrew found it "really magical" to watch Elton work on the album with Brandi, he recalled how the Tiny Dancer singer was "exhausted" and filled with self-doubt, having come to the studio after finishing his lengthy Farewell Yellow Brick Road retirement tour.

He said: "He was exhausted. He was doubting himself. He was very self-conscious, very insecure at times, and we helped lift him up.

"And when he got through it all, he was so proud, and it was a really, really special, special time. I'll never forget."

The producer noted Elton writes songs "in a way really no one else writes" as a result of his lengthy partnership with Bernie Taupin.

He explained: "He takes [a lyric], puts it up on the piano, reads it, sees a movie scene in his head, and then scores the movie.

"And then as he's scoring the movie, he starts singing the words, fitting them into the chords and coming up with melodies based on the words and the phonetics of the words..

"[He] can't do it without the words because what makes him feel like a story."