In Britain, if you are driving a car, you must stick to certain speed limits. For example, in towns and villages the speed limit is 30 mph, though on some roads you are allowed to drive at 40 mph.

　　Many drivers do not observe the speed limits. They drive too fast. So on some roads, particularly where there have been accidents in the past, the police have installed speed cameras. Speed cameras measure the speed of vehicles and photograph the number plates of cars that are travelling too fast. If you are caught by a speed camera, you are fined and get three penalty points on your driving licence.

　　Speed cameras in Britain are painted bright yellow. They are easy to see, and this means that drivers have time to slow down if necessary. Nonetheless some motorists hate speed cameras. They think that the government uses speed cameras to raise money and to persecute innocent motorists. Some drivers have even tried to destroy or remove speed cameras.

　　Last year, Mr John Hopwood was caught by speed cameras twice on successive days. The first time he was doing 48mph in a 40 mph zone. The second time he was doing 40 mph where the speed limit was 30 mph. He decided to try to get out of the second offence by removing the “40” sign from the road where he was caught the first time, and placing it on a lamp-post near the spot where he was caught the second time. He photographed the sign, and sent the photograph to the court with a letter saying that it was unreasonable to prosecute him for doing 41mph where there was a sign saying that the speed limit was 40mph. Unfortunately the police soon realised that the sign had been moved. They employed an expert to analyse photographs of the sign in both its new location and the old one, and proved that they were in fact the same sign. Mr Hopwood pleaded guilty in court to having moved it. The court may decide to send him to prison. He would have done better to pay the speeding fine. Even better to have obeyed the speed limits.

　　Note: These three expressions mean the same:

　　you must stick to the speed limit

　　you must observe the speed limit

　　you must obey the speed limit

　　“He was doing 48 mph” means “he was driving at 48 mph”