Seems to me that trolling can range from being unpleasant to being criminal. In cases where the police get involved the troller has committed an offense.
Robert Riley and Peter Nunn were both prosecuted for sending grossly offensive and/or menacing messages. This is the law they were prosecuted under;
Communications Act 2003 Section 127(1) covers offensive and threatening messages sent over a "public" electronic communications network. Since 2010 it has increasingly been used to arrest and prosecute individuals for messages posted to sites such as Twitter and Facebook. Section 127(2) covers causing annoyance by sending messages known to be false, which is one of the laws that hoax-999 callers can be prosecuted under.
However, not all such messages will lead to prosecution. The guidelines say;
The Director of Public Prosecutions' 'interim guidelines' (December 2012) for social media prosecutions include the use of Section 127. These attempt to limit the usage of Section 127, to cases which go beyond those which are "offensive, shocking or disturbing; or satirical, iconoclastic or rude; or the expression of unpopular; or unfashionable opinion about serious or trivial matters, or banter or humour, even if distasteful to some or painful to those subjected to it".[1]
https://wiki.openrightsgroup.org/wiki/Communications_Act_2003/Section_127I am concluding that calling someone a troll is meaningless. The word has been hijacked by the media and is used to suggest that everyone making posts on the internet which upset others are criminals. Clearly they aren't. In the case of the McCanns no one has been prosecuted as far as I know despite the campaign waged by their supporters.
