January 10 1969 was the last day that all four Beatles would be present at Twickenham Studios in London in order to continue on the "Get Back" project with rehearsals of two McCartney songs: "Get Back" and what was assumed to be the first song of a live set "Two of Us". Beatles' music publishing and majority owner of "Northern Songs Ltd" visited the set in the morning as well.
Things got heated later in the day between John and George (not Paul and George) as some books have indicated - the "I'll play whatever you want me to play" scene from the "Let It Be" film was taken from January 06 1969 and not on this day the 10th.
It must have been pretty heated as this was the rehearsal session which saw George Harrison leave the site and return home; essentially quitting the band. He was the second to quit after Ringo had left during the White Album sessions a year earlier but eventually returning. Same would happen with George.
There is some footage of the remaining Beatles jamming with Yoko from later in the day as well. There is an attempt to continue rehearsing with some tunes such as "Maxwell's Silver Hammer" and "Don't Let Me Down" being performed but all of this is of no use at the moment. The session ends with discussion and review of the day between the band members and the director of the television/movie special. Nothing from this day appears in the final cut of the film.