The History of Cat’s Eyes

Cat's eyes are one of those inventions so simple and so effective that it's hard to imagine the roads without them. Found on around 99% of UK roads, these small reflective studs guide millions of drivers safely through darkness, fog and rain every night. But where did they come from? The answer is a genuinely charming piece of British history involving a foggy road, a stray cat, and a road-mender named Percy Shaw. Here's the full story, and what those different-coloured studs actually mean for you as a driver today.

Cat's eyes were invented by Percy Shaw, a road-mender from Halifax in West Yorkshire. The story behind the invention has become a famous piece of motoring folklore.

As the tale goes, Shaw was driving home one foggy night in 1933 when he reached a dangerous stretch of road. He normally navigated in the dark by following the reflection of his headlights in the polished steel tram tracks. But on this particular night the fog was so thick that the tracks gave off no reflection, and he couldn't make out where the road curved away toward the hillside.

Then he had a stroke of luck: his headlights caught the eyes of a stray cat sitting at the roadside, reflecting brightly back at him. That reflection showed him exactly where the edge of the road was, and the idea was born. If he could replicate the way a cat's eyes reflected light, he could guide drivers safely along dark and dangerous roads. Shaw realised that as cars grew more popular and more people drove at night, headlights alone wouldn't be enough to keep them safe.

Shaw registered his patent for the cat's eye in 1934, but it took several years to perfect the design. The challenge wasn't just making the studs bright enough to light the road at night, it was also making them tough enough to survive all weathers and the constant weight of vehicles driving over them.

By 1937 he had won a government contract to mass-produce them. Shaw's design was ingenious: four glass beads set into a rubber moulding, mounted on a cast-iron base, then buried and fixed into the road with asphalt. He positioned the glass beads in pairs facing opposite directions, so they reflected light back to drivers approaching from either way.

The clever part was how they survived being driven over. When a vehicle passed across a cat's eye, the rubber moulding was designed to sink down into the road, dropping the glass beads safely beneath the surface so they weren't damaged. Even better, Shaw built in a self-cleaning mechanism: the cast-iron base collected rainwater, and every time a vehicle pressed the dome down, that water washed over the glass beads, keeping them clean and reflective without any maintenance.

His company, Reflecting Roadstuds Ltd, went on to produce over a million cat's eyes a year at its peak, exporting them across the world.

The original cat's eyes were white, but today you'll see several colours on UK roads, and each one tells you something specific. Knowing them is genuinely useful, especially when driving at night or in poor visibility:

White studs mark the lane dividers or the centre of the road.

Red studs mark the left-hand edge of the carriageway, so if you see red reflecting back, you're drifting too far to the left.

Amber studs mark the central reservation of a dual carriageway or motorway.

Green studs mark the edge of the main carriageway at slip roads and lay-bys, where side roads join or leave.

Green and yellow studs indicate temporary changes to the lane layout, typically at roadworks.

Reading these colours instinctively is a real safety skill. If the studs to your right are amber, you know you're beside the central reservation; if the ones to your left turn red, you know where the road edge is. On a dark motorway in the rain, that colour-coding is doing a lot of quiet work to keep you in the right place.

Cat's eyes are a brilliantly simple British invention, dreamed up by Percy Shaw in 1933 after a stray cat's reflective eyes showed him the way through the fog. Patented in 1934 and mass-produced from 1937, they've been keeping drivers safe for the best part of a century. And while the story is a lovely bit of history, the practical takeaway matters too: learning what the different coloured studs mean will make you a safer, more confident driver whenever the light fades.

Understanding the roads, from cat's eyes to junctions, is all part of becoming a confident driver. Find your local DRIVE instructor and book your lessons today.