The Police here (Dyfed-Powys Police) are running a campaign "Get Insured or Get it Seized" which highlights their powers to seize vehicles that are on the roads unlawfully, such as when there is no valid insurance in force. In an article in the local newspaper they spoke of "persons driving without the correct documents", and I enquired of the Police if this meant carrying one's Certificate of Insurance. A helpful lady in their Press Office replied as follows:
“Since the inception of special powers (Section 165) given to the Police we can now seize any vehicle whereby the driver cannot prove that he/she has valid insurance for the vehicle or an officer suspects that the vehicle is being driven without insurance. I would advise you to visit the MIB's (Motor Insurers' Bureau) database www.askmid.com
and input your registration number - it will indicate whether your insurance company has registered your vehicle as insured. If it comes up RED and shows the vehicle as uninsured get in contact with your insurance company as you could be at risk of having your vehicle seized under Section 165.”