From the pictures it is clear that all Beatles attended (together with director Michael Lindsay-Hogg and Patti, Linda & Yoko)
John is sitting next to Ringo.
and in some pictures Yoko is sitting next to him.
Panorama picture of the screening room
Afterwards everybody had lunch
John & Yoko
and Linda & Yoko
Disclaimer: I do not own the pictures, nor do I know who does. I have found these on several fan sites and only reproduce them here in low-resolution for historical reasons, not for copy-right infringments.