Jimmy Page and company lambasted JT for their lack of live improvisation. And then Barre improvises an iconic guitar solo on the first take with Page looking on.
“I compose most of my songs on acoustic, and therefore the way I play the guitar impacts on the way the song sounds.
"I wrote the main riff [to ‘Aqualung’] in a hotel room in New York City. At the time I was trying to write songs that had [single-note] lines that would translate on the electric. I knew the ‘Aqualung’ riff would work well because it pretty much echoes the vocal melody.
"In this case, the riff I played for Martin Barre [Jethro Tull lead guitarist] on the acoustic instantly became the song’s electric part.”