The Beatles on Top of the Pops. 16th June 1966. (Photo by Daily Mirror/Daily Mirror/Mirrorpix via Getty Images)Mirrorpix | Mirrorpix | Getty ImagesLONDON — A new Beatles song featuring the complete Fab Four will be released Thursday, 45 years after John Lennon began writing it — with the help of artificial intelligence.Titled “Now And Then,” it will debut on BBC radio at 2 p.m. London time (10 p.m. ET) at the same time as its release on streaming platforms, including Spotify and Apple Music. The track will be available on CD and vinyl from Friday.A short film detailing the making of the “last Beatles song” was published to the band’s official YouTube channel Wednesday and has already gained more than 1.4 million views.Lennon recorded a demo of the song with piano and vocals at his home in New York two years before he was murdered in 1980.Fellow band members Paul McCartney, George Harrison and Ringo Starr worked on the song in 1995 with the aim of releasing it in a Beatles retrospective project, but it was left unfinished due to the technical difficulty of using the vocals on Lennon’s tape.Work on completing the song revived more than two decades later, when director Peter Jackson was producing the mammoth eight-hour Beatles documentary “Get Back.”Artificial intelligence software — which Jackson used to clean up archive footage in the film — isolated Lennon’s voice on “Now And Then,” removed background noise and improved sound quality.”We were able to take John’s voice and get it pure through this AI, so that then we could mix the record as you would normally do. It gives you some sort of leeway,” McCartney said earlier this year.Harrison died in 2001 and will feature in rhythm guitar sections recorded during the 1995 project.