If you know who any of these people are, you can start a private prosecution in the magistrates' court (section 6(1) of the Prosecution of Offence Act 1985 preserves this ancient right). There is the risk that the CPS, via the DPP, will intervene and take over the case only to offer a nolle prosequi (statement to have the case not proceeded with) but it might wake them up and result in action by the police. But this is all more theory than practice. Taking the route suggested above,or invoking the might of the local press or the Daily Mail or other national paper is more likely to produce a result.