Veteran singer Lou Reed had the time of his life recording an album with Metallica, likening the experience to receiving "a Ferrari for free".
The ageing musician teamed up with the heavy rock group to record Lulu earlier this year (11) and he admits the relaxed working environment was key to their creativity.
He tells, "Nobody thought about anything. It was just a great opportunity to play together. I had a certain sound in my head that I wanted to try to get, and I got it. The way we did this is that if everybody didn't agree, we didn't do it. It wasn't majority rules - it was all together or nothing."
The collaboration did not sit well with some Metallica fans, but Reed has brushed off the criticism and insists the recording process is one he'll never forget.
He adds, "They're into heavy metal, I'm into heavy guitar, so it was no big stretch. They were so ready to go, it was thrilling. It's like someone gave you a Ferrari for free."