The fact that The Beatles were able to make new music with John Lennon after his death is something we will never see again. They may have been mulling over the idea of the Fab Four coming back together again, but once Lennon was assassinated in 1980 and George Harrison passed away in 2001, the idea of any Beatles reunion was gone for good. The Beatles Anthology and the recent release of ‘Now and Then’ may have been fun gifts for fans to listen to later, but ‘Free As a Bird’ began with a rocky start for Paul McCartney.

Then again, anything that McCartney handled that had to do with Lennon would have to be given proper attention. This was his musical soulmate who had somehow left music for him to finish, so there was little room for him to screw everything up. But this wasn’t just a Lennon/McCartney song…this was a Beatles track, and everyone needed to be represented.

Even though it was gut-wrenching knowing that producer George Martin wouldn’t be present in the control room for the band’s next venture, getting ELO frontman Jeff Lynne was probably the best choice. This was going to be a new Beatles song, after all, so why not go with the guy who sounds like the band’s Sgt Pepper was carried on for an entire career?

The only problem was that Lynne was a little bit too close to the rest of McCartney’s bandmates. He had already been a part of the Traveling Wilburys with Harrison and had produced his album Cloud Nine, which featured Ringo Starr on the song ‘When We Was Fab’. It may have just been a sly nod to The Beatles, but singing a song about them and not having one of the still-breathing members in the video would ruffle a few feathers.

Once McCartney realised what Lynne was doing, he started to get on board, especially when working on finishing different pieces that Lennon hadn’t finished yet. Every great Beatles song needs a guitar solo, though, and old habits between McCartney and Harrison reared their heads when it came for Harrison to write something.

When talking about putting the song together, McCartney gave his bandmate adamant instructions about what he wanted out of the solo, later recalling in Still the Greatest, “I told Jeff that I was slightly worried about this because I thought it would sound a little bit like ‘My Sweet Lord’. I felt like the song shouldn’t be pulled in any way…It should sound like a Beatles song”.

If you know any of the baggage that the band had in the past, this could have turned ugly really fast. There are already a number of Beatles songs in which McCartney deliberately tried to limit Harrison’s contributions, which is half the reason why Harrison left the band in the first place during the sessions for Let It Be.

What Harrison ended up delivering, though, was absolutely perfect for the song. Having just the right amount of melodic touches, the subtle guitar licks toe the line between the bluesy licks Harrison played in his early days while embracing the slide guitar, which had practically become a signature of his solo career.

Though the band worked hard trying to make the most out of the demo, this might be considered one of the most classic Beatles songs in their catalogue, especially since every premiere songwriter in the group had a hand in writing and singing pieces of it. There’s no telling what Lennon would have done with ‘Free as a Bird’ had he survived long enough to complete it, but hearing his old mates pay tribute to his song is one of the most heartfelt moments in all of rock music.