Final answer:
The historical event discussed is the first Beatles reunion sessions in 1994, where George Harrison, Paul McCartney, and Ringo Starr worked on the song 'Free as a Bird.'
Step-by-step explanation:
From November 11th through 28th of 1994, the historic first Beatles reunion sessions are held, with work beginning on 'Free as a Bird'.
In this process, producer Jeff Lynne presented a cleaned-up new version of an original John Lennon demo recording to which George Harrison added bluesy slide guitar, and he and Paul McCartney contributed with acoustic guitars.
Paul McCartney also played bass and doubled John Lennon's original piano parts, Ringo Starr played drums, and vocals were added by all three surviving Beatles.