The surviving members of the group attended a party at the London music Mecca alongside Paul's wife Nancy Shevell, Ringo's spouse Barbara Bach, and stars such as Nile Rodgers and Taron Egerton.
The pair were pictured arriving separately, missing the opportunity to recreate "Abbey Road"'s iconic album artwork featuring The Beatles walking on the pedestrian crossing outside Abbey Road Studios together, as fans had earlier in the day.
Although the record was the penultimate one the group released, coming out on 26 September 1969, it was the final one they recorded as a band before their 1970 split.
Paul has also given an interview to Take That musician Gary Barlow for his BBC Radio 2 show, in which he describes how The Beatles, who had their first hit in 1962, grew as songwriters.
"I think that was purely that we were young guys who just would've got bored if we'd have got a formula," he says. "So it's like 'Let's do this', we were just trying to amuse ourselves and entertain ourselves and so we were getting better. And lyrics, consequently, got better, the arrangements got a little bit more intriguing and we cut them back to make some bluesy thing or whatever".
"It was always just trying to do something that we liked, that entertained ourselves and in doing so we assumed that the fans would pick it up".
"Abbey Road" has been reissued to mark the 50th anniversary, hitting retailers on Friday, September 27.