Is it illegal to warn of a speed trap?

After I saw a police motorcycle parked up in a layby I flashed my lights at some oncoming bikers to warn them as I drove away. I don’t think they were actually speeding but I was then followed by another police motorcyclist. He stopped me and gave me a fixed penalty notice saying I had broken the law. I have looked into it but cannot find anything about using headlights to warn other drivers as being wrong. Can you confirm if he was right to issue a fine?
Phil Jones, by email


There is an offence of warning others about a speed trap.

  1. Warning the driver of a motor vehicle who is driving in excess of the speed limit that there is a speed trap amounts to obstructing a constable in the execution of his duty contrary to s.89(2) of the Police Act 1996: based on the case of Bastable –v- Little from 1907
  1. Betts –v- Stevens from 1910 – this confirmed that there must be some act of warning and there must be evidence that the driver was breaking the law.

The policeman was probably thinking of the case of Bastable when he gave you the fine but he may not have acted in accordance with the law as you have not mentioned that there was actually a mobile speed camera. If you have not yet paid the fine I would seek clarification from the police that they have complied with the law.


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