Driving at 71mph in a 60 on the M4 got him a six‑month ban: would you risk £346 now?

On the M4 and M5, changing limits, gantry signs and discreet cameras mean even tiny errors can snowball into expensive trouble.

A driver from Dorset found that out after a routine camera check recorded a modest excess during a variable limit. His case, and another from Swindon, shows how the same stretch can produce very different outcomes for motorists.

What the court heard

Andrew Richard Patterson, 57, from Trent near Sherborne in Dorset, drove a Volkswagen Golf through a variable 60mph section covering the M4 between junctions 19 and 20 and the M5 between junctions 15 and 17 on Monday, 9 December 2024. Cameras recorded 71mph while the reduced limit was active.

Magistrates at Bath imposed a financial penalty and a driving disqualification on Friday, 15 August. The court list recorded a fine and costs alongside the ban.

Strongest penalties in the Patterson case: £346 fine, £138 surcharge, £90 costs, six‑month disqualification.

He entered a guilty plea. The publicly available summary did not specify whether the disqualification followed the totting‑up of 12 points or a separate discretionary ban for the offence.

Another motorist, same corridors, different outcome

In a separate incident, Kelly Stubbs, 43, from Swindon, was recorded at 72mph while a 60mph limit applied on the M5 northbound between junctions 17 and 16 and on the M4 between junctions 19 and 20 on 31 August 2024. She received a fine and points rather than a ban.

Second case outcome: £146 fine, £58 surcharge, £110 costs, three penalty points for 72mph in a 60mph variable limit.

Variable limits on the M4 and M5

The M4 and M5 around the Almondsbury interchange operate with live, overhead variable limits to manage congestion, incidents and roadworks. When gantries show a lower speed inside a red‑ringed sign, that limit is enforced until cancelled by a national speed limit sign or a higher posted limit. The technology targets steady traffic flow and shorter stop‑start waves, especially through junctions 19–20 on the M4 and 15–17 on the M5.

How enforcement works

Approved digital systems monitor each lane. When a limit activates, enforcement follows. The cameras are designed to capture offences reliably in all conditions. Previous national guidance suggested tolerances may apply, but drivers have no entitlement to exceed a posted limit. If the sign shows 60, that is the legal maximum.

Why a six‑month ban for 71mph?

For 71mph in a signed 60mph limit, the Sentencing Council’s band A range usually applies: a fine linked to weekly income and three points, or a short discretionary disqualification. A six‑month ban typically signals the totting‑up rules have been triggered by reaching 12 points within three years, or that the court chose a lengthier disqualification for reasons not detailed in the listing. The Bath court record did not explain the basis, and that is common with brief registers.

What penalties usually look like

• Band A (for 60mph zones: 61–75mph): fine of 25–75% of weekly income and 3 points, or a short ban.
• Band B (76–85mph): higher fine and 4–6 points, or a ban of 7–28 days.
• Band C (86mph+): highest fine band and 6 points, or a longer ban.

Courts also add a victim surcharge and prosecution costs. That is why two fines for similar speeds can differ in total value: income, plea timing and costs shape the final figure.

What this means for you on these stretches

The two cases show how a small excess during a variable limit can bring very different consequences depending on the driver’s record and the court’s assessment. The safest approach on the M4/M5 corridors is to treat every gantry as live and plan for reductions you cannot yet see.

A variable limit applies to every lane while it is displayed in a red circle, even if traffic looks clear ahead.

Smart ways to avoid the flash

• Watch the nearest gantry for your lane; limits can differ by lane when arrows are active.
• Keep speed stable with cruise control or a speed limiter when traffic allows.
• Trust live signs over your sat‑nav; digital maps often lag behind temporary restrictions.
• Keep safe distance; sudden braking for a late‑seen limit risks a rear‑end collision.
• Look for the national speed limit sign before accelerating; do not rely on a blank gantry.
• Check your tyre pressures; an under‑reading speedometer can nudge you over.

The time you think you save

Running at 70mph instead of 60mph for two miles on a reduced stretch feels brisk, but the gain is tiny. At 70mph, two miles take about 1 minute 43 seconds. At 60mph, two miles take 2 minutes. The difference is roughly 17 seconds. Against the risk of points, higher insurance and the costs listed above, that 17 seconds looks poor value.

If a notice lands on your doormat

• Act quickly: a Notice of Intended Prosecution sets deadlines to identify the driver.
• Check the details: date, time, location, and whether a variable limit was active.
• Consider your licence position: if you are near 12 points, legal advice can clarify options.
• Mitigation helps at court: clean record, genuine error, and early guilty pleas can influence sentencing.

Why these stretches see so many tickets

The M4/M5 interchange funnels long‑distance and local traffic through a dense cluster of slip roads. Variable limits smooth merging and protect roadworks. When demand spikes, limits drop fast and stay low until traffic stabilises. Drivers who miss a single gantry often continue at pre‑set cruise speeds and drift into enforcement zones. The cameras do not need patrol cars or a traffic stop; a clear image and a data match to the registered keeper start the process.

Insurance and cost impact

Three points can nudge annual premiums up by tens or hundreds of pounds depending on the insurer. A six‑month disqualification often prompts a steeper rise after reinstatement, and some policies exclude cover during a ban. Add the fine, the surcharge and court costs, and a single moment above a 60mph variable limit can cost several hundred pounds within weeks.

Takeaway for regular users of the M4 and M5

Plan for dynamic limits on every journey through junctions 19–20 (M4) and 15–17 (M5). Expect reductions at peak times, after incidents, and around roadworks. Set a speed limiter a notch under the displayed limit to give yourself a buffer. If you are unsure whether the restriction has ended, hold your speed until you pass a clear cancellation sign.

Variable limits can feel frustrating when the road looks empty. They exist to prevent abrupt braking and to cut the surge‑and‑stop waves that cause collisions. The penalties in these two cases show that even low‑level excesses draw attention on smart motorway corridors, and the costs stack up quickly when they do.