The star was "nervous" and "irritable", partly because he was recovering from a hip replacement, he said, but also because he was working in a new way - writing live in the studio with Carlile, producer Andrew Watt and long-term lyricist Bernie Taupin. "It was an enormous challenge, getting those four people together," he told the BBC. "And the challenge really was at my feet. "I was very nervous [because] I wanted the album to stand a certain way, but you can't always guarantee it will. "I think my nerves and my insecurities and my doubt led to a few bad behaviour moments, which was just about frustrations within myself." Once they had recorded the opening track, The Rose of Laura Nyro, "everything fell into place", Sir Elton said. "In two and a half weeks, we recorded 14 songs and finished them." The album's release was delayed last year after an eye infection left the star with vision difficulties. Last week, he told the Times he could no longer watch his sons playing rugby.