Do you flash other drivers to warn about mobile speed cameras?

[MattDillonsEyebrows]

As I was driving to work this morning, in one of the villages there was a mobile speed van. Some drivers flashed (quite vigorously in some cases) to let me know it was there, others didn’t and I just wondered if you flash to let others know there’s a mobile speed camera?

I generally don’t speed so I don’t think it would have mattered to me, but it did make me check my speed, make sure I was driving under, rather than on the speed limit and possibly drive more carefully than normal.

For what it’s worth, I always do flash other cars to warn them and I see it as a good deed, but it got me thinking about why some people don’t.

Is it that they just don’t think about it? Do they think flashing is dangerous (it is mumsnet! 😂)? Do they think if someone is speeding it’s on them to not speed?

Am I actually helping criminals and not doing the good deed I think I am?

Just generally wondering, I don’t think there’s a right or wrong…. is there?

Yes I am a flasher

Unless I can see someone speeding significantly, then yes I do warn people by flashing my lights that there is a speed trap. I don't want someone who is doing 43 in a 40 zone to get points on their driving licence. If someone is doing 50-55, or more, then fuck 'em, they can get the points on their licence.

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Common sense really just drive at the required speed and don't be a twat.

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I flash for one section. They often have a mobile speed camera at the bottom of a steep hill ad it's easy to drift over the speed limit. I truly believe it's nothing more than revenue raising and if one is there I will flash cars (unless there is someone obviously massively over the limit at which point I think FAFO).

I flash cars if there are horses on the road though and flash sometimes to warm oncoming cars if there is another hazard of some sort.

I probably would too in that case or if there's a similar hazard round a blind bend

By flashing when the intended recipient understands and slows down, you are preventing speeding, so it is fair enough.

No. I’ve seen others do it, but it honestly wouldn’t occur to me. I’m not sure I would even clock a mobile speed camera unless it was pointing towards me!

Depends. If it’s ages after - no. If it’s too soon after I’m going to assume someone has let them know. If there’s a sweet spot though and I’m out of view of the officer and someone is coming along the other way without a clue what’s waiting around the bend, then yes.

Would you tell a burglar to run away because the police are coming? No? Then stop telling scum speeding drivers to slow down bcause they are going to get caught for their selfish, anti-social driving. Even better, flash them and wave your arms at them when there aren't any police around to tell them what you think of their driving.

As the parent of someone hit by a speeding car I don't want to hear from the usual "it doesn't matter" crowd. It does. Your license permits you to drive according to the law, nothing more or less.

The law respectfully disagrees

https://www.theguardian.com/uk/2011/jan/04/driver-flashed-lights-motorists-speed-trap

No. I don't speed and I don't expect others to. Apart from anything else it's illegal.

Fascinating, thanks for your replies,

I actually thought there would be more flashers and I didn't realise it is illegal. I also flash if there is a hazard like a horse rider or load of cyclists in the road, and see it as a similar thing. People have always flashed me and I tend to be grateful for reasons as PP said if I happen to be slightly over the speed limit, it makes me go under rather than on.

You might prevent speeding on that single occasion. But letting the idiot get caught and be fined would hopefully prevent speeding on more than one occasion.

Not for a speed camera no, it wouldn't occur to me to do so. I do flash to warn people of hazards such as sheep in the road or a flood.

Any time anyone flashes me I get paranoid that I have left my bag or something on the roof. Usually it's just because they think I am on full beam (when I'm not). Our main road is straight but very rolling, so when you are on the top of a crest, to a car in the oncoming dip it looks like you are on high beams, even though you are not. This makes people from not round here incredibly irate for some reason and they flash like maniacs.

Apparently, the laudable action of encouraging people to check their speed is regarded as hindering lawful police enforcement.

Yes, it's also illegal in many places in Europe too: Here's some info, UK included!

Based on 2026 information, here are the key countries where this action is restricted or against the law:
Switzerland: Warning of speed cameras by any means—including flashing headlights—is strictly prohibited.
Germany: It is illegal to use high beams to flash oncoming traffic to warn of police or speed checks. It is also illegal to use apps that alert you to speed cameras.
United Kingdom: Under Rule 110 of the Highway Code, headlights should only be used to warn of your presence, not to send messages. Doing so can lead to fines of up to £1,000 for "[wilfully obstructing a constable in the execution of their duty]".
France: While not as strictly penalised as using warning devices (which is very strict), warning others can be deemed a violation of traffic safety rules.
Spain: Generally permitted, but using lights to create a hazard or in a way that blinds others is illegal. Speed camera detectors are illegal to use, and warning others is generally discouraged.
Belgium: Using a horn or flashing lights to communicate, including warnings, is generally forbidden.
Norway: It is prohibited to warn of speed checks.

absolutely NO!

Flashing to warn people of speed traps is illegal in some countries, like Australia.

It is hindering law enforcement! - but more important it hinders prevention of accidents by catching the criminals, punishing them and hopefully making them think twice about doing it again, thus potentially saving lives.

The sort of person who only checks their speed when alerted to the fact that they are about to get caught is not a safe driver and needs to be stopped.

oh stop being such a bloody busy

Yes to cars who are clearly driving at or close to the speed limit. Any cars obviously speeding quite a bit over the speed limit absolutely not

It wouldn't occur to me and no I wouldn't because they shouldn't be speeding.

I've been warned a couple of times and I never understand why they're flashing. I'm usually driving at at least 10mph below the speed limit anyway, which according to mumsnet is evil.

I just assume I'm doing something wrong or the car is on fire and I haven't noticed. It makes me very anxious! I wish people wouldn't assume that everyone is on their wavelength.

I don’t think you’re meant to but yes I sometimes do. There’s one near us sometimes and someone a bit further down the road makes a sign and puts it on the traffic island to warn people! I’m sure they’d get into a lot of bother if they were caught doing that!

That’s a tad dramatic