Led Zeppelin's Gallows Pole is based on an old blues song called "Gallis Pole," which was popularized by Leadbelly. The song is considered "traditional," meaning the author is unknown.
Jimmy Page got the idea after hearing the version by the California folk singer Fred Gerlach. Page explained when previewing the song for Melody Maker: "He was one of the first white people on Folkways records to get involved in Leadbelly. We have completely rearranged it and changed the verse. Robert wrote a set of new lyrics. That's John Paul Jones on mandolin and bass, and I'm playing the banjo, 6-string acoustic, 12-string and electric guitar. The bloke swinging on the gallows pole is saying wait for his relatives to arrive. The drumming builds nicely."
The lyrics are about a man trying to delay his hanging until his friends and family can rescue him. Although there are many versions of this song, Led Zeppelin's is unusual in that it ends with the hangman hanging the protagonist despite all of his bribes. Most other versions end with the hangman setting the protagonist free.
A similar folk song called "Slack Your Rope" was sung by an Arkansan named Jimmie Driftwood. He adapted the words from a fifteenth century British Ballad when any crime could be paid off with money right up to the last step of the gallows. In his version, the criminal is definitely a woman and her lover rides up and pays her fee.
This is the only Led Zeppelin song that features a banjo. Jimmy Page wrote it on a banjo he borrowed from John Paul Jones. He had never played the banjo before. From: https://www.songfacts.com/facts/led-zeppelin/gallows-pole
