The background vocals were sung by Donovan of "Mellow Yellow
" fame. Donovan was recording at Willesden's Morgan Studios around the same time as Alice, and got roped into the session.
In a 2016 Songfacts interview with Donovan
, he told the story: "Here was this guy that I just met. He played me the song, and said, 'Would you like to put a vocal on?' I said, 'OK. Give me the chorus.' I listened to the chorus, and his guitar player was playing like Keith Richards - something very powerful that he'd learned from Keith or from Brian Jones in the Stones. And when I listened to the chorus, I said, 'OK. I'll give it a go.'
But I learned something: I had to sing in falsetto. Power bands in Britain had already learned that to have a singer in a power rock outfit, you need a singer who can go into falsetto. That's why you've got Robert Plant in Zeppelin, Jon Anderson
with Yes. They have to raise their voices into the high range.Chris Squire
of Yes, who was a friend at the time, I said, 'Why is it?' And he said, 'Well, it's very easy. If you want your voice to be heard, you've got to climb above the guitars in the mid-range, or else you won't even hear the vocal.' And it's true.
So, I immediately said, 'Hey Alice, what do you think of [singing falsetto] Biiiillion Dollar Babies
? So I did the falsetto, Alice loved it, and then I forgot about it, and never even thought about it, until someone told me later, it went to #1. And I was half the vocal! So Alice and I, when we meet, we have a chuckle and a laugh about it. It was a great pleasure. And the best thing about it was nobody knew it was me for so long!"