And even before the necessity test (1st Jan 2006) came in to force, one could still have been arrested for any offence under certain PACE rules and conditions.
In your scenarion though, a police officer writing numbers down will always be a bone of contention. Fight it all the way and without photographic evidence you will win. All you need to do is put a seed of doubt in the magistrats head and hey presto!!
I am not an anarchist and may be vilified, but if you are brave enoughto fight it, I guarantee without any real evidence, you will win. It will probably not even go to court in the first place if thou protests initially.