coconutty - (and other concerned parties who want the full weight of the law used....)you cant "prosecute" for malicious communications - its not crime recordable, and as far as i can see on the face of it, it would be dealt with as malicious comms. (unless there is more to it)
the most that can happen to this "troll" is they could be issued a fixed penalty notice (unless there is more to it of course) I have dealt with a few cases of mal comms but only once have i considered actually giving a ticket, the suspect had a vendetta against certain public agencies that they felt had "wronged" them, and so waged a campaign of abuse and nuisance communications against them and was very persistent and extremely abusive.
i think its probably unrealistic to expect much more than this. There is a procedure to most things - first (minor) offences dont generally get dealt with harshly. It would not be practical or realistic to expect this person to end up in court. Even though they may be a prolific "troll" this could possibly be the first time they have come to police attention. If they continue, or commit other offences that could fall under public order, or there are aggravating factors then it may well be different.
but people, trolls - who think they cannot be traced because they are hiding behind an assumed identity on a faceless forum need to realise that they can be found and identified.
i really think we need a change in the law to catch up with the internet - the law is lagging behind technology a bit i think. The law as it stands is quite vague and its a case of trying to see what fits - we need clear legislation to cover what happens now on line.