Heathrow Director- "The frequencies remain the same but by clever switching, all aircraft can hear each other and the controller. Dashed clever, what?"
You must be speaking of that amazing contraption they call cross-coupling. Doesn't exist at Scottish where it's normal ops to have 4 or 5 sectors bandboxed at 19:00 with 1 controller operating them, using at least 3 frequencies whilst monitoring at least 2 others. Now thats single manning.