The problem is the current Labour government has a history of ignoring even the largest and best planned campaigns and marches. Look how much notice they took of the countryside alliance march last year and the "stop the war" march, which incidentally was the largest march in British history, (not that I agree with the latter of course).
Even the British Conservative party are soft on criminals and hostile to empowering the public to use realistic force (and certainly not armed force) to stop criminals. The establishment of a high profile vigilante like organisation would send a message to the government, and the Torys, that either the state must solve this problem or victims will band together in groups and take the law into their own hands. Such an organisation would have the added benefit of keeping this issue in the public eye and stopping it from just disappearing once the Martin fiasco stops making headlines.