"If your minicab's not booked, it's just a stranger's car," read the posters with the image of the deserted car park. "Ten sexual assaults are committed by illegal cab drivers in London every month," say the TV ads so scary that they have a 15 certificate. We've all seen the campaigns, which are sponsored by the police. We know not to get into a cab that we didn't pre-book. We look out for the "distinctive licence discs" displayed in the windows.
Our hearts sank, then, when police who were looking for the missing Swindon woman, Sian O'Callaghan, whose body has now been found in Gloucestershire, called for sightings of a green Toyota Avensis "with taxi markings".
Police have become more sensitive about the way that they talk to women about crimes that affect us. They steer clear of telling us that if there's a dangerous rapist on the streets we must all stay at home. They finally seem to understand that it's not women who are to blame. But they find it harder to explain how we should stay safe. They probably haven't had to try finding a cab late at night when it's raining.
A couple of years ago, a scam was discovered whereby drivers were registering their cars as private hire vehicles in order to avoid paying the London congestion charge. For an £82 registration fee, followed by £27 a year, any clever driver could have that all-important Transport for London (TfL) roundel stuck to his windscreens, front and back.
When I called TfL on Friday to ask what's being done about this, I was reassured that "All private hire vehicles must pass an annual inspection... two MOT tests each year [and] a rigorous annual safety check", and that "all individuals applying to become a licensed taxi or private hire driver have to undergo an enhanced Criminal Records Bureau [CRB] check", among other things. But these rigorous checks are separate for driver and car. It seems that any old rapist can buy a TfL sticker.
That doesn't alter the fact that nobody should get into a cab that isn't pre-booked. But it's not always as simple as TfL would like. I've got into a car that I found outside a locked-up local minicab office, whose driver told me, "Of course I work here: I've got the TfL sticker to prove it." I've had a cabbie refuse to confirm the name under which I'd booked and pre-paid. You have to tell me your name," he said, "otherwise any stranger might jump in my cab and get a free lift home."
I asked him why any stranger would want a free lift to my house at 2am, at which point he told me to get out.
I've also called a cab to pick me up in a minor red-light district. The minicab office couldn't tell me my driver's car model, make, or licence number, leaving me to peer into every car with a male driver that slowed down. I found the cab eventually, but I wouldn't recommend this practice.
The London cab firm Addison Lee is particularly successful with women because it sends a text upon booking describing the car in detail and giving the driver's mobile phone number. But Addison Lee is not always available, even in London.
You can receive three registered cab firm numbers by texting "CAB" to 60835, says TfL, which also gives the following advice:
w Never approach a minicab on the street or accept the offer of a ride; the drivers are acting illegally. Only black cabs can pick passengers up on the street.
w Always book, so that there is a record of your journey.
w When your booked cab arrives, check it's for you and sit in the back.It's not always easy, but it is important. And most important of all is to remember that "taxi markings" mean nothing.