The song is likely to be Now And Then, which John Lennon recorded as a demo two years before his death.
In an interview with BBC Radio 4 that aired on Tuesday (Jun 13), McCartney did not name the track but said the technology was used on “a demo that John had, that we worked on”. “He was able to extricate John’s voice from a ropey little bit of cassette,” McCartney said.
