Peter Green had been working on the 1969 piece for some time before the addition to the band of 18 year old guitarist Danny Kirwan.
I love the whole Peter Green era yet when Danny Kirwin entered, these ambient instrumentals really came together. I believe he and Green had similar vision for the band's direction.
The line up at the time was Peter Green - guitar, Danny Kirwan - guitar, John McVie - bass and Mick Fleetwood - drums.
It has been suggested that the piece is associated with the metaphorical use of the word albatross to mean a wearisome burden. The use of the word "Albatross" to mean an encumbrance found somebody's neck is an allusion to Coleridge's poem "The Rime of the Ancient Mariner" (1798). Not a coincidence that the LP title, "The Pious Bird of Good Omen", alludes to and quotes from the Coleridge poem.
The LP release also contained "Black Magic Woman" unknown by most to be a Green composition.
Personal note: Another favorite song of mine is post Green's departure. "Sunny Side Of Heaven."(currently on podcast written by Kirwin on 1972's 'Bare Trees'. "Danny's Chant" is another highlight although with the addition of Bob Welch "Sentimental Lady" garnered the pop accolades.
Albatross was 1st released as single with "Jigsaw Puzzle Blues" as Kirwin B-side.
Apologies for going link nutty.
