“QS Alarm Systems” burglar alarm, Hereford • From the deepest depths of west England comes this ancient red bell box, labelled with tiny wonky lettering. QS is more likely to stand for Quick Service than Quaint Sounder, though it could be Quick Shock, as the initials have been parted by a lightning flash reminiscent of the one that Dame David Bowie (© Tom Hibbert, RIP) sports on the cover of Aladdin Sane. Here’s how to recreate that alluring 1970s look, if you’re interested. • Spotted: Town centre, Hereford, Herefordshire, HR1, England, 2008 • Politics: In the Conservative constituency of Hereford and South Herefordshire
Burglar Alarm Britain 
That is a dummy for sure. The shape was called a ‘C’ type. The dummy covers had no back plates, but lugs at the top ack to hand over two screws with two screw tags at te bottom, although in te picture only oe is shown. To substantiate ths, note that no cover screw/bot exists.
Is that the black wall I can see through the vents, so it’s only a dummy. QS could not stand for Quality Systems, look at the fixing screw at the bottom not srewed fully in.
Maybe it stands for Quite Shonky
Mike, don’t say that, that particular type of box usually has a dark backplate with the sounder in the middle so you can’t really tell!
although I do agree about the back looking like the wall!
From what I’ve seen some companies back in 85 like vigilante intruder alarms used a vented dummy type c but actually had a bell ether on the wall or on a wooden plate. And sometimes people would drill to holes on ether the left or right hand side of the box and have a tamper screwed in not only that but if the tamper didn’t fit perfectly thay would put a spoon to extend the reach of the tamper switch so it would work how mad is that!
From what I’ve seen some companies back in 85 like vigilante intruder alarms used a vented dummy type c but actually had a bell ether on the wall or on a wooden plate. And sometimes people would drill to holes on ether the left or right hand side of the box and have a tamper screwed in not only that but if the tamper didn’t fit perfectly thay would put a spoon to extend the reach of the tamper switch so it would work how mad is that!