Apart from protecting the likes of the Bay City Rollers and the Osmonds from their screaming fans, it also gave rock fans a real pain in the neck. If you were unlucky enough to get tickets in the first few rows of the stalls, you were lucky if you could even see the top of your heroes' heads.
Looking at this picture, the reason for the elevated stage becomes clear; when the place was a cinema they had a full orchestra or band in front of the curtains.
Unlike 'real' theatres, where the orchestra plays in a pit, at Green's, they played on the floor.
Sadly, come 1985, the music finally stopped and the whole place was eventually torn down in 1989.