According to online information service Advicenow, "cyclists still seem to be unaware of the law that came into effect on 21 October 2005, which allows them to fasten flashing lights to their bikes."

We're told that "because attaching flashing bulbs to the bike frame used to be illegal, most bikers are still clipping them to clothing or bags. This means the beam can be easily obscured or might flash the wrong way, making cyclists unwilling prey for unobservant cars or buses."

We can't say we're totally convinced by this - most people either never knew that it was illegal in the first place or simply didn't care. And certainly the police didn't care much, being generally more concerned with global terrorism and drunken behaviour than minor transgressions of the laws governing bicycle lighting.

That said, we're more than happy to draw your attention to the fact that, as of 21 October 2005 you're no longer breaking a law that no-one cared about by having a flashing light on your bike. Obviously, having it on your bike doesn't render it instantly immune to being obscured or pointing the wrong way - we see plenty of seatpost-mounted lights being blocked by objects as diverse as mudguards, seat packs or the rider's jacket, or simply pointing sideways or at the ground.

One thing we didn't know about the new law is that it also formalised the use of blue flashing lights on bikes ridden by members of the emergency services, so if you see a bike with blue flashing lights on it it's probably a good idea to get out of the way. Don't hop up on to the pavement, though...