On a motorway, a few seconds at the wrong speed can upend a driver’s life. Near the M4 and M5 link, one motorist was banned from driving. An automatic speed camera captured 68mph in a 60mph zone on that controlled stretch. Another driver on the same link was recorded at 71mph under the same limit. Together, their cases show how variable limits, roadside technology and court decisions shape trips on this route.
How a routine journey on the M4 became a court case
Ben McCarthy, 51, from Cromhall in South Gloucestershire, set out in a Range Rover Sport on the M4. He travelled between Junctions 19 and 20, then continued on the M5 from Junctions 15 to 17. Above the lanes, electronic signs showed a 60mph limit. Traffic moved steadily in each lane.
On that journey, his speed rose to 68mph while the restriction remained fixed at 60mph across the stretch. An automatic enforcement system linked to a roadside speed camera measured the excess and stored the evidence. The reading triggered a prosecution that later brought him to Bath Law Courts.
Magistrates fined McCarthy £461 for the offence and added a £184 surcharge plus £110 in prosecution costs. Coverage sometimes rounded this to a £460 fine, yet the official overall total reached £755. He also received a six month disqualification from driving, completely removing him from the roads.
What the speed camera recorded on the M4 and M5
McCarthy’s appearance in court did not mark an isolated event on this part of the motorway network. Other drivers have misjudged the same variable limit between the M4 and M5, then faced similar prosecutions. The link near Bristol has become a focus point for repeated enforcement cases in recent months.
One of them is Andrew Richard Patterson, 57, from Trent in Sherborne, Dorset, driving a Volkswagen Golf. On Monday 9 December 2024 he travelled on the same M4 J19–20 and M5 J15–17 route. Electronic boards displayed a 60mph variable limit above the carriageway. Traffic conditions looked normal to passing motorists.
Despite that display, Patterson’s Golf was measured at 71mph in the signed 60mph zone. Evidence from the enforcement system and a speed camera reading went before magistrates. They fined him £346, added a £138 surcharge and £90 costs, and imposed a six month ban for that journey.
Variable limits, smart motorways and the rules drivers must follow
The M4 forms a major route between London and South West Wales, carrying dense traffic through the region near Bristol. To manage that flow, National Highways uses smart motorway technology and variable limits. These controls help smooth traffic when congestion builds, incidents occur ahead or bad weather affects visibility.
Digital signs on gantries and roadside panels show each new limit above the lanes whenever traffic managers lower the speed. Drivers must obey that figure and, when a screen falls blank, keep the last limit, not a speed camera flash. That habit prevents confusion when signs briefly change or flicker.
National Highways recognises that the reason for a slower limit may not always be obvious to drivers. Motorists must still follow the figure shown on the boards because it reflects conditions beyond their view. When systems change a limit, screens may briefly flash while internal self checks run.
Why strict speed camera enforcement targets small excesses in speed
During these self checks, a flashing pattern on the screens can look to motorists like the burst from a camera. Some drivers fear they have already been photographed the moment the number changes. In reality the pattern simply shows the system testing itself before it settles on a new display.
To prevent unfair penalties, police forces work with National Highways to build in a delay before enforcement begins. That buffer gives drivers time to notice the sign and slow safely. Only after that period do systems and any linked speed camera enforce the lower limit across the lanes.
These safeguards sit alongside the wider framework for UK motorway limits explained in official guidance. Variable numbers help reduce sudden braking, keep distances safer and smooth heavy flows through bottlenecks. That is why small excesses above a posted limit can draw strong penalties, because they undermine that carefully managed balance.
What happens after a speeding offence reaches the authorities
When a motorist exceeds a limit, enforcement does not always end with an automatic ticket and fixed penalty. Depending on the speed recorded and previous history, police may consider different responses. Some drivers receive offers of education or awareness rather than an immediate pile up of penalty points.
In many regions, eligible drivers can attend a speed awareness course instead of collecting points. They qualify when they meet guidelines set by the National Police Chiefs’ Council. The excess must fall within a set band and they must not have taken it in the past three years.
Only the police can offer such courses, with courts having no power to order them as an alternative. When cases like the two M4 offences reach magistrates, the focus turns to fines, bans and costs. Evidence from roadside systems and any speed camera readings then shapes the penalties imposed.
What these motorway bans should signal to drivers
Taken together, the stories of McCarthy and Patterson show how small excesses above a variable limit change everything. A brief decision on speed can turn an ordinary trip into months off the road. Their fines, surcharges and bans underline that every posted number on a smart motorway carries legal weight. For anyone using this stretch of the M4 and M5, the safest habit is to watch the signs. They should treat each speed camera as part of that system.
