Nearly every electric guitar player in the land knows Led Zeppelin's classic song Stairway to Heaven, but its success apparently came about by accident.
The track was written by Robert Plant and Jimmy Page and first appeared on the Led Zeppelin IV album in 1971, but it was never issued as a single.
However, it did go on to become very popular with radio disc jockeys, despite being more than eight minutes long.
According to Charles Cross, author of a recent biography on the rock band, its length was one of the reasons it was played on the radio so often.
"I literally had a 100 DJs swear to me that they only played the song because they needed a long break to go and smoke a cigarette," he told the New York Post.
Cross added that they would not have had time to smoke a full cigarette if it had been any shorter.
The song was included in the setlist at Led Zeppelin's one-off reunion gig at the O2 Arena in London two years ago.
However, Robert Plant has so far ruled out the possibility of a full-time reformation, preferring instead to concentrate on his collaboration with Alison Krauss.
Page has recently been working on the movie documentary It Might Get Loud, while bass guitar player John Paul Jones is now performing with Dave Grohl in Them Crooked Vultures.
