The Screen Room projected films on 35mm film print on a Kalee-21 projector. The mechanism would have been new technology in the 1940s but the lamphouse and the sound-head would have been much more recent.
The lamphouse bulb is a 1000Watt bulb to give a bright enough picture.
35mm film is projected at 24 frames per second which means if you watch a 2 hour film you will have watched nearly 175,000 individual frames of film and if you were to unroll the whole film it would be about 2 miles long.
A 35mm projector is becoming an increasing rare sight in cinema projection rooms as the move to digital projection is well underway.
Because of the small size of the Screen Room cinema, there was no room to project from the back of the auditorium over the heads of the audience as in most cinemas. We projected on to the back of the screen which required us to bounce the image off a mirror at 45 degrees so the picture wasn’t back-to-front on the screen. This is a quite rare way of projecting, but not unique - screen 2 in the Kinema-in-the-Woods in Woodhall Spa, Lincolnshire, UK does the same thing.