Brian May said 1917 classic is his favourite piece of music of all time

As the electric guitarist of the world's most successful band after The Beatles, Sir Brian May has contributed plenty through Queen's music back catalogue.

In fact, when he took part in back in 2002, he nominated his very own We Will Rock You as one of his castaway tracks.

At the end, the guest is always asked which single piece of music they would save if they could only keep one from the waves.

Basically, it's a question of what's your all-time favourite. And just like many other guests, Sir Brian struggled a bit with his choice.

The Queen legend replied: "Oh, God. Now that's an awful question. Um... d'you know, I think it's gonna be No 1. I think it's gonna be the Planets Suite, because there's so much in there. There's so much depth, and there are still things which I need to find out about it. I think I'd probably take that."

Gustav Holst's The Planets is a 1917 seven-movement orchestral suite, with each movement named after a planet of the Solar System and embodying the character of the Greek/Roman god they're named after.

For Desert Island Discs, Dr Brian, who has a PhD in astrophysics, chose the fifth movement, Saturn - The Bringer of Old Age, which was Holst's favourite of The Planets. After it played, he said serenely, "Umm. Gets me every time".

On the monologue he once wrote about the movement, Sir Brian said: "It was actually about one winter's night, and the progress of the stars, so it was kind of an astronomical monologue." Asked what his castaway book would be alongside The Bible and the Complete Works of William Shakespeare, the rocker chose the first book in The Space Trilogy: "My book is Out Of The Silent Planet by C S Lewis. Written, I suppose almost as a children's book, but it's a very adult kind of children's book. It's a very spiritual thing. It's on the face of it a science fiction story, but underneath it is a view of the Universe, which I really hope is true."