It's all down to the magistrates unfortunately, if you're lucky you'll get a lay judge, i.e. a proper official rather than do gooder magistrates with too much time on their hands.
Speeding offences should not be handled by magistrates at all, there should be some other body who actually know something about driving, roads and safety.
Macduff, your comments, while perfectly true, are not helpful.
You can't make judgements like that when you don't know the facts. There are many dual carriageways in the UK with an unrealistic 30 limit, there are also many residential roads where the limit should be less than 30.
If there's a camera sited on such a road the likelihood is that it's there to make money. I have very rarely seen a camera sited where it's actually needed. The only way camera's provide any form of additional safety is if they are sited at suitable intervals all the way along the road in question, which is usually pretty impractical unless you go down the SPEC's route. Otherwise they actually increase the likelihood of an accident, or simply move the so called black spot further down the same road.