The old comms system was replaced in January 2009 by Ewan Connor (Technical Manager) with help from Mal, Jamie McQuilkin and various others. The new system is one ring with two lines:
(If anyones interested the reason why we didn't go the other way, ie SL Followspot, Indoor hall, Stage Cupboard, is that there was no suitable point to drop cable down to indoor hall and we didn't really want to drill any more holes lest the building collapse.)
The whole thing is now cabled with three-core xlr:
Within the boxes, there is a choc block connecting the incoming and outgoing xlr components with three small wires. These wires then connect to the corresponding xlr pins.