With a few exceptions (such as the specific law against using a mobile phone while driving) there are hardly any 'precise' motoring laws. Instead there are 'general' laws, where it's left up to the police (and the Crown Prosecution Service) to decide whether you've broken them.
For example, there is no law which specifically states that you can't drive your car down the right-hand-side of the road in a normal two-way street. If a policeman sees you doing it he has to decide whether your actions amount to 'driving without due care and attention', 'careless driving' or 'dangerous driving'. However if you were driving a milk float along the right-hand-side of a well-lit and deserted road at 5am you'd almost certainly not be committing any of those offences. (i.e. it's neither legal nor illegal to drive on the 'wrong' side of the road; it depends upon the circumstances).
If you drive with a lot of snow on the roof of your car it can result in a following driver finding himself in a 'snow storm' from the snow blowing off your roof. "Driving a vehicle on a public road without consideration for other road users" is an offence under Section 3 of the Road Traffic Act 1988:
http://www.cps.gov.uk...s_of_bad_driving/#a16
So (since that Act came into force) it has always been possible for a policeman to interpret driving with excessive snow on the roof as an offence. It may be that the police are now starting to clamp down on this but it's not a new law.
Chris