In the eyes of the law, travelling just 1mph over the speed limit is deemed an offence - it is just at the discretion of the police as to whether to issue a penalty. The National Police Chiefs’ Council (NPCC) recommends that constabularies give a leeway of 10% + 2mph, but it is crucial to remember that this is only guidance and it is entirely within the powers of the constabulary to decide how, or if at all, to apply this guidance. You can read our guide to speeding fines here - www.honestjohn.co.uk/advice/driving-advice/speedin.../