You will see many photos of times past where studios had playback monitors wall mounted. Many times they are are on dollies or have wheels mounted for as-needed applications. A good suppostion is that they tended to be high up when wall mounted to get them out of the way and also get them where they can direct over a large group of musicians.
As for these in Studio Two, you don't see them in older photos of the room. Nor the lights. So perhaps they were both installed for the various "live" from Abbey Roads and other concert productions. Funny that these vintage speakers (without the diffraction lenses) were hoisted up there. Maybe there are still dozens around in the old store rooms within the facility.