While 84 per cent of drivers caught speeding in Cumbria end up with penalty points, the figure drops to as low as 35 per cent in London.
The dramatic gulf was revealed by a Sunday Telegraph analysis of the recently-published accounts of all 38 safety camera partnerships across England and Wales for 2006-7.
Motoring organisations voiced concern at the findings and warned that drivers could be encouraged to take a "more cavalier approach" to speed cameras in parts of the country where enforcement is lax.
There are several ways in which motorists caught speeding can escape points on their licence. In some areas, first-time offenders who have drifted slightly over the limit are offered the chance to avoid penalty points by agreeing to pay to attend a "speed awareness" course instead.
Others may lodge successful appeals, or simply find the case dropped by the police or courts.
Drivers who use illegal "cloned" number plates, or do not register their details with the DVLA, often go untraced if they are caught by a speed camera. So do drivers of foreign-registered vehicles.
Across England and Wales, 3.06 million drivers were caught speeding and issued with Notices of Intended Prosecution, the first step towards handing out penalty points, yet only 1.75 million went on to pay a Fixed Penalty Notice fine and receive points on their licence – a punishment rate of 57 per cent.
The area-by-area breakdown shows that the lowest enforcement rates are often in urban areas, which are likely to have higher numbers of illegal drivers and foreign drivers.
Areas where more than half of speeding motorists escaped without penalty points include Avon and Somerset where only 36 per cent received penalty points, Mid and South Wales (41 per cent), West Yorkshire (45 per cent), Essex (47 per cent) and Merseyside (48 per cent).
Critics warned that the wide range in results risked undermining public faith in speed cameras. A spokesman for the Institute of Advanced Motorists said: "We feel that the variation in prosecution levels for speed camera offences depending on the location does not inspire confidence.
"If the speeding offence is committed, then the follow-through prosecution arrangements should be consistent, no matter where you are – after all, the law is the same wherever you are.
"If it becomes known that you are less likely to be prosecuted for speeding in Essex than in Gloucestershire, for example, that may encourage a more cavalier approach to speed cameras."
Experts said there were many reasons for the patchwork pattern of enforcement.
"In urban areas there is much greater movement, people tend to change addresses more often and their details are often not sent to the DVLA," said Kevin Delaney, former head of traffic at Scotland Yard.
"As a result the DVLA records are less likely to be accurate than in rural areas and the stockbroker belt.
"Some forces give traffic more priority than others. Some will put more effort into cameras and following up cases.
"In others, where traffic is less of a priority, they are less likely to be prosecuted in the first place, and if they give an excuse that is more likely to be accepted. In cities, the main priorities are organized crime, terrorism and drugs."
His views were largely echoed by Rob Gifford, executive director of the Parliamentary Advisory Council for Transport Safety.
"The figures, for example, for the Met are very poor – not surprising, given the nature of the London driving population," he said.
"So, part of the lottery effect is explained by police activity and part by the compliance of the driving population in that area."
The figures suggest that rural forces tend to take a tougher line. "We are more efficient and we believe there has to be a deterrent to reduce casualties in Cumbria," said Jan Sjorup, a spokesman for the local Safety Camera Partnership.
"Our policies are working and we are already ahead of the Government's casualty reduction targets."
The low rate of issuing penalty points in London is due in part to a policy of offering some speeding motorists the chance to attend a speed awareness course as an alternative to a fine and penalty points.
But a spokesman for the London Safety Camera Partnership pointed to other enforcement problems in the capital.
"A lack of court time has hindered our efforts to increase the number of prosecutions for these offences," the spokesman said.
"We are working with the Courts Service and Crown Prosecution Service to increase the amount of court time we are given to pursue prosecutions."