Are Keybury the Mulberry of security?

It’s not just fashion that changes through the years – here at Keybury we delved into the thirty-three years of bell-box design history and highlighted the key changes.

The journey began with the vented plastic bell box. The Achilles heel of this design was that it allowed burglars to inject builder’s expanding-foam through the vents muffling the sound of the bells ringing. The phrase ‘stuff & cut’ became popular at this time – the foam muted the alarm and often in addition the telephone was cut, meaning the alarm didn’t ring through to the police. This prompted a change of bell box design.

Intruder Alarm Bell Boxes Through The Years

The unvented bell box was put into manufacture. This ensured foam couldn’t be injected into the alarm box, however thieves soon saw a flaw, handheld power drills saw them drilling a hole in the plastic bell box, to once again fill the bell box with foam.

To try and avoid the vandalising of the bell boxes and thieves breaking into houses, the design of bell changed again. This saw the development of the metal bell box, ensuring that they were unable to be drilled. This design worked well however the bell boxes began to rust and look unsightly.

Intruder Alarm Bell Boxes Through The Years

Then came the biggest redesign of all! This saw a combination of a metal inner housing and an external polycarbonate lid. The back and inner lid were both metal with a polycarbonate outer lid. This meant the box did not rust, and the box could not be drilled. A seemingly fool proof bell box – Voilà!

Intruder Alarm Bell Boxes Through The Years

Today’s bell boxes are largely the same design but now the whole box illuminates at night providing the best visual deterrent yet.

Intruder Alarm Bell Boxes Through The Years


The development of the bell boxes over the past thirty-three years has kept Keybury customers at the cutting edge of both protection and aesthetic design. Until the next movement and beyond… you can be sure to feel safe at home with the latest Keybury design.

Contact us to find out the latest upgrades you can make on your alarm system.

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