At Tesco in Lewisham, a reassuring sign says the local minicab firm will give you a reference number, their drivers must help you with your shopping, they must be clean and well presented and they must wear a badge.
Unfortunately, it does not always work like that. I called, booked a cab and decided to hold out until I was satisfied the driver was from the company I had called.
An unmarked car - it is illegal to advertise on the cars - arrived. I refused to give my reference number, the driver couldn't tell me what it was although he should have been in radio contact with the office. I refused to get in and, somewhat alarmingly, he got out, then finally pulled his identity card out of his back pocket. I eventually got into the car, only to be greeted with a stony, angry - and quite terrifying - silence.
A Tesco spokeswoman said they had introduced the charter because they were concerned about the safety of their customers.
Although they had not received any other complaints, the cab firm has given an assurance all drivers will wear their badges.