I have received a speeding ticket for speeding on the M5 around Droitwich. Mobile speed camera.

The reason I write, is that my speed was captured as 79mph.

I cruise control atc78, so won't argue with 79, however, my understanding is that 10% + 2 and no action.

On a motorway, that is 79, hence my 78 cruise control.

They must capture 2/3 of motorists, on a motorway, if they are going that low.

All thoughts welcome!

The 10% + 2 is a fallacy. The stated limit is the limit. You need to reset your cc to 70.

I think the problem here is that many people believe the 10% + 2 mph rule is a legal right. However, it's not a legal rule but rather a guideline that police and safety camera partnerships may use if they wish.

Because you weren’t doing much over the limit, you’ll probably get the option of a speed awareness course ( unless you’ve done one in the last three years ).

The advantages are that you don’t get points, you’re not obliged to notify your insurers, and you can now do them at home, online. They cost about the same as a speeding fine.

https://www.lancashiretelegraph.co.uk/n ... ffer-zone/



The tolerance varies between police forces so the 10% + 3 mph that applies in Lancashire may not apply in other counties.

My first 3 points and speeding fine were on the M5 between Bristol & Exeter in 1991 and I was doing less than you. At the time I was told the police in that section of the motorway were particularly strict

"cruise control at c78, so won't argue with 79"

Weird. With cc set at 78, I would have expected your GPS speed to be 75 at most. Sure you were not within roadworks or variable speed limit etc?

bfcfan1882 wrote: ↑

Wed Sep 17, 2025 2:15 pm

"cruise control at c78, so won't argue with 79"

Weird. With cc set at 78, I would have expected your GPS speed to be 75 at most. Sure you were not within roadworks or variable speed limit etc?

depends on the car - more modern EVs will have much more accurate speedometers than a 10 year old petrol car for example. As stated above the 10% +2 is only a guideline, which is in place to account for older cars with varying tyre pressures etc and all the other issues that can affect the actual speedometer reading. Usually, and from my experience, my car will show 75 on the dash when my sat nav (iPhone Waze) is showing closer to 70, so I know that as long as I stay below 75 on my dashboard then I'll be fine. Lower speeds are usually much less affected so the same difference does not apply to 30 where in my case my car shows 30 and sat nav is usually 29 or 30 as well.

I found that you can allow for 10% maximum on the M6, even in roadworks. Nothing more.

Leisure wrote: ↑

Wed Sep 17, 2025 1:52 pm

The 10% + 2 is a fallacy. The stated limit is the limit. You need to reset your cc to 70.

Its almost laughable when you think about it, Its 70 but we will let you do 79

gawthorpe_view wrote: ↑

Wed Sep 17, 2025 2:07 pm

https://www.lancashiretelegraph.co.uk/n ... ffer-zone/



The tolerance varies between police forces so the 10% + 3 mph that applies in Lancashire may not apply in other counties.

That article is from 2019, is it still accurate?

Burnley1989 wrote: ↑

Wed Sep 17, 2025 2:28 pm

Its almost laughable when you think about it, Its 70 but we will let you do 79

Does seem a little generous but wouldn't like to see no leeway

Why would you set your CC at 79, when the limits 70, and there are speed cameras on almost every gantry?.

Is there an official tolerance?
Technically, no — there’s no legal rule that says you’re allowed to go over the limit by a certain amount. The speed limit is the absolute maximum, and going even 1 mph over it is breaking the law.

However, most police forces follow guidance from the National Police Chiefs’ Council (NPCC), which recommends a buffer to account for speedometer inaccuracies and human error.

What’s the ‘10% + 2 mph’ rule?
This is the informal guideline most forces use. It means you might not be penalised unless you're doing:

35 mph in a 30 zone

46 mph in a 40 zone

57 mph in a 50 zone

68 mph in a 60 zone

79 mph in a 70 zone

So, for example, if you’re doing 34 in a 30 zone, you’ll probably be fine. But push it to 36 and you’re into ticket territory.

That said, this isn’t law — it’s discretion, and it varies slightly between police forces and camera types.

Does it apply to all speed cameras?
Not always. There are several types of speed cameras used in the UK — including:

Fixed speed cameras

Mobile speed cameras (in vans or roadside)

Average speed cameras

Red light/speed-on-green cameras

Most fixed and average speed cameras follow the NPCC’s 10% + 2 guideline. But mobile cameras? They’re known to be less forgiving — and they can catch you even a couple of mph over the limit.

Can I be fined for going 31 in a 30?
Yes — in theory. But in practice, that’s unlikely. Most forces won’t issue a fine unless you’re at least hitting that 10% + 2 threshold.

Still, that doesn't mean you're safe to treat the limit as a target you can push. Speed limits are set for a reason — and enforcement is ultimately up to each local force.

What happens if I do get caught?
If you’re caught just over the limit, you might be offered a speed awareness course (as long as you haven’t done one recently). Otherwise, you’ll typically get:

A £100 fine

Three penalty points on your licence

For more serious offences (i.e. way over the limit), you could face a higher fine, more points, or even a court appearance and a ban.

The takeaway
That “10% + 2” buffer? It’s a guideline, not a guarantee. You could still be fined for going over the limit — even slightly — especially if you’re unlucky or the camera doesn’t follow the standard rules.

So the best bet? Stick to the limit. Not just to avoid fines, but to keep yourself and everyone else on the road safe.

I got picked up by a fixed gantry camera near Gordano Services on the M5 in Bristol. The variable speed signs weren't lit, and I was doing 79 mph.

I remember a news item at the time (about ten years ago) stating that particular camera had made more money than any other in the country.

I do a lot of motorway miles, I've found in general that majority of people stick to speed limits these days, people certainly go slower than they did 10-15 years ago.

I stick to the limits as I'm usually in a hire car. Not worth the hassle to get somewhere a couple of mins earlier

There's really no excuse for doing 79 mph. (Especially if you've got cruise control!!!) That's illegal on every road in the country. People can get caught doing 40 in a 30 zone simply because they missed a speed limit sign, a genuine mistake, but there can't be any mistake about thinking the limit is 80.

The reason 10%+2 is a guide and not a buffer, is that context matters. Doing 77 on an empty motorway in bright sunshine is reasonable if not encouraged, but doing 71 at night in thick fog is ludicrously stupid.

dsr wrote: ↑

Wed Sep 17, 2025 2:57 pm

There's really no excuse for doing 79 mph. (Especially if you've got cruise control!!!) That's illegal on every road in the country. People can get caught doing 40 in a 30 zone simply because they missed a speed limit sign, a genuine mistake, but there can't be any mistake about thinking the limit is 80.

Can't disagree with you DSRI- had a company car for 40 years doing 35,000-40,000 miles pa and picked up around 7 or 8 speeding fines in that period. Retired 6 years ago and since paying for my own fuel have kept a clean sheet. Funny that

1) my brothers friend got clocked at 76 I think it was so the ACPO guidelines apparently don't need to be met

2) Use android auto/apple car play with google maps and it will show you where mobile speed cameras are

tarkys_ears wrote: ↑

Wed Sep 17, 2025 3:44 pm

1) my brothers friend got clocked at 76 I think it was so the ACPO guidelines apparently don't need to be met

2) Use android auto/apple car play with google maps and it will show you where mobile speed cameras are

Don't trust Google maps to pick up Every speed camera, it doesn't. It relys on people reporting mobile cameras, if you're the first through, tuff luck.

The buffers were built in years ago, to take into account any mistakes with the cameras, nowadays they are far more accurate, so if it says you're doing 78, you are doing 78.

I completed a driver awareness course last week and this 10% rule came up. I still have the transcript from the session...

"Speaking of speed limits, there’s a common belief, often called the 10% rule, which states that the speed limit is not enforced until you exceed it by at least 10%. However, the 10% rule isn’t really a rule at all. You can be stopped and given a ticket for speeding at any speed faster than the official limit. Ultimately, it’s up to the discretion of the police officer whether they stop you. If you want to be sure that you aren’t pulled over, always stick to the limit."

I've been done a couple of times on smart motorways, much to my annoyance. On both occasions I was over the speed limit by less than the 10% + 2 mentioned in the OP, so I can categorically state it's not a thing!

ollieclarets8 wrote: ↑

Wed Sep 17, 2025 1:53 pm

I think the problem here is that many people believe the 10% + 2 mph rule is a legal right. However, it's not a legal rule but rather a guideline that police and safety camera partnerships may use if they wish.

A bit like VAR then.

Leisure wrote: ↑

Wed Sep 17, 2025 2:33 pm

That article is from 2019, is it still accurate?

https://www.confused.com/compare-car-in ... tolerances

It appears so.

Plissken wrote: ↑

Wed Sep 17, 2025 3:25 pm

The reason 10%+2 is a guide and not a buffer, is that context matters. Doing 77 on an empty motorway in bright sunshine is reasonable if not encouraged, but doing 71 at night in thick fog is ludicrously stupid.

Yeah, mine was at 5 am on a glorious summer day, virtually empty motorway.

But a fixed camera ain't gonna worry about any of that.

North Wales Police are very hot on speeding.

Darnhill Claret wrote: ↑

Wed Sep 17, 2025 5:17 pm

Nort Wales Police are very hot on speeding.

So are North Yorkshire. There are no fixed speed cameras in N Yorks, but they don't half love getting out in the vans.

Got done on M1 two years back, did the speed awareness course and downloaded Radar Bot on my phone. It still works and screams at you if your approaching a camera at mote than the limit on any particular section. It just can't get mobile units.

I think you'll need to accept things and go for the SA course.

Unless you’re driving in Italy whereupon if you stick to the speed limit you run the risk of causing a pile up with the idiots overtaking on blind bends and solid white line roads!.

As for the UK, I Think I heard a comment on a radio 4 programme (so it must be true) that the 10% thing was being phased out across the land.

If you reside in Wales you may as well ditch the car.

"I cruise control atc78"

No more questions your honour

Row x wrote: ↑

Wed Sep 17, 2025 2:43 pm

Why would you set your CC at 79, when the limits 70, and there are speed cameras on almost every gantry?.

Exactly. In fact I'm quite surprised that we are having this debate.

There is a level of arrogance and lack of respect for other road users in setting a cruise control above the legal limit of 70mph.

North Yorkshire Police say they PROSECUTE at 10% + 2...ie. 79mph in a 70 zone. But it is their choice, not a legal requirement.
Given that speedos (not swimming trunks) are good to +/-3mph? Setting your cruise 1mph below the potental outside linit of prosecution level is a bit risqué IMO

Contest it Ian, fight it until the bitter end, not that I think you've a cat in hells chance of getting it overturned but the more time you spend trying then the less you spend on this messageboard.

No sympathy for anyone who can't obey the speed limit.

dougcollins wrote: ↑

Wed Sep 17, 2025 5:18 pm

So are North Yorkshire. There are no fixed speed cameras in N Yorks, but they don't half love getting out in the vans.

Always one somewhere on the A64 between the M1 and the end of the York bypass.

nonayclaret wrote: ↑

Wed Sep 17, 2025 6:44 pm

North Yorkshire Police say they PROSECUTE at 10% + 2...ie. 79mph in a 70 zone. But it is their choice, not a legal requirement...

A couple of years ago I was one in group of five motorbikes that got stopped near Scarborough doing sixty four in a sixty limit. All good natured, the officers even opened the conversation by telling us that this was intended only to be a warning/advice stop and so it proved for four of us. The fifth - he's from Bolton, so what can you expect - got arsey and despite advice from the rest of us, insisted on explaining to the two policemen how the 10%•2 'rule' meant that they 'couldn't touch' him for the offence... Cost him £110 and three points, didn't even get the speed awareness option

If it’s a mobile camera they may consider the road conditions ,if it’s very wet they may think 79 is way too fast ,if your 78/79 in a 70 limit then there’s only one person to blame.

I don’t understand why people don’t set speed control to the legal limit and have done with it, there’s little or nothing to be gained by exceeding the given limit, and the penalties can be huge. My part of the world is no different to UK, too many cars on the road going too fast, too many crazy drivers Many people think the speed cameras are a tax grab, however the more $$ going into the local coffers means more can be spent on infrastructure improvements etc……….or more to waste on rubbish undertakings, but that’s another story

Elizabeth wrote: ↑

Wed Sep 17, 2025 2:40 pm

Does seem a little generous but wouldn't like to see no leeway

There probably is a little leeway because the speed dial in your car, generally speaking, isn't 100% accurate.
My mechanic friend reckons GPS (SatNav) is more accurate.

TheFamilyCat wrote: ↑

Wed Sep 17, 2025 8:30 pm

Always one somewhere on the A64 between the M1 and the end of the York bypass.

Isn't there just.

That is why the 10% thing came in but I suspect all modern cars are much more accurate and I know people get done for being 2mph over the limit

Sort of related, I got caught recently and I’m going on a speed awareness course online. You can actually book it with any of the official providers so I used ChatGPT to find the cheapest and booked in with Hartlepool Council (£79).

Juan Tanamera wrote: ↑

Wed Sep 17, 2025 8:58 pm

There probably is a little leeway because the speed dial in your car, generally speaking, isn't 100% accurate.
My mechanic friend reckons GPS (SatNav) is more accurate.

That is correct, unlike speedometers, GPS is not directly influenced by tire pressure, tire wear, temperature, or road surface conditions, which can all alter the relationship between axle rotation and actual speed.

exilecanada wrote: ↑

Wed Sep 17, 2025 9:09 pm

That is correct, unlike speedometers, GPS is not directly influenced by tire pressure, tire wear, temperature, or road surface conditions, which can all alter the relationship between axle rotation and actual speed.

My mate in Bedford wasn't happy that he'd done 200 mph on his Kawasaki until GPS confirmed it.

He had a visit from the law 'for his own safety' but it was a forwards facing speed camera and they couldn't prove it was him.

Who on earth would set their cruise control to 78. That's incredibly dangerous driving and fully deserves a punishment.

An ex copper friend of mine (North Yorks police) explained this as that the norm for not being prosecuted is 10% plus 1 mph.
In his words the second mph is “theirs”. So they would not normally prosecute at 78mph but at 79mph plus.

Set your cruise control to 70, problem solved. If you're in a rush,set off earlier.

AmbleClaret wrote: ↑

Wed Sep 17, 2025 9:50 pm

Set your cruise control to 70, problem solved. If you're in a rush,set off earlier.

That's a bit of a contradiction to be honest.

If you'd set off earlier- ie on time- you wouldn't be in a rush.

AmbleClaret wrote: ↑

Wed Sep 17, 2025 9:50 pm

Set your cruise control to 70, problem solved. If you're in a rush,set off earlier.

That’s a little more than ambling, I’d say, Amble.

IanMcL wrote: ↑

Wed Sep 17, 2025 1:50 pm

I have received a speeding ticket for speeding on the M5 around Droitwich. Mobile speed camera.

The reason I write, is that my speed was captured as 79mph.

I cruise control atc78, so won't argue with 79, however, my understanding is that 10% + 2 and no action.

On a motorway, that is 79, hence my 78 cruise control.

They must capture 2/3 of motorists, on a motorway, if they are going that low.

All thoughts welcome!

Waaah, I was breaking the law and they collared me for it.

If you’re after sympathy it’s in the dictionary between sh!t and syphillis.

A few years ago I was following my wife in our cars through a small north Yorkshire town.
She was given a speeding notice whereas i wasn’t and yet our speeds were exactly same.