The instrumental track, “Meridian West”, came about when Dylan invited the Waterboys to a recording session in Church Studios in north London in 1985, where he was working with former Eurythmics musician Dave Stewart.
Waterboys frontman Mike Scott told Mojo magazine that the track was born out of an extended jam with the legendary singer.
"Bob wasn't working in his usual way, which is, he's got a song, and everybody tries to guess what the chords are,” he explained.
"He was playing instrumentals that he'd written with Dave and the idea was that later he would put lyrics on them. So, we played there for two or three hours and there was one particularly lovely instrumental.”
The band revisited the song the following day with Dylan’s band, experimenting with a slower version, when, said Scott, “Just by good fortune I’d pressed record on my cassette machine.”
Scott has previously written about the band’s jamming session with Dylan in his 2012 memoir Adventures of a Waterboy.
"His face, so familiar from film and photograph, looked more Eastern in real life, as if he were an inscrutable Chinaman or a Zen Master,” he wrote. "He was dressed in jeans and red shirt with a blue scarf, and having shaken our hands (he seemed genuinely pleased to see us) he reverted to his afternoon's pursuit, playing ceaseless lead guitar, coaxing burbling, bluesy sounds from a Fender Stratocaster.
"We found spaces to sit and joined in what turned out to be a slow, sexy instrumental. To our disappointment Bob didn't sing, just kept playing the burbling guitar, even in the breaks between takes."
The forgotten jam resurfaced as Scott was putting together the six-CD, 95-track box-set detailing the creation of This Is the Sea - an album that contained the Waterboys’ anthemic single “The Whole of the Moon”, and described by Scott as "the final, fully realized expression of the early Waterboys sound begun on the albums The Waterboys and A Pagan Place."
After discovering the recording, Scott says: "We contacted Bob's management to see if he would allow us to include it. They came back and said, 'Oh yeah, no problem. Bob remembers that instrumental ... it's called ‘Meridian West’.”
The box-set compilation will be released in 2024, and comes as Wonka actor Timothée Chalamet prepares to play Dylan in upcoming biopic, A Complete Unknown. The film will chronicle the period in 1965 when Dylan “went electric”, a move which upset his original folk fanbase and famously saw him branded as “Judas” at a gig in Manchester’s Free Trade Hall.