The scenes at the funeral of Constable Ronan Kerr were unprecedented, heart-rending and emotionally draining. There have been many watershed moments in the past 40 years, but none which surpassed the spirit of unity shown in the heart of Co Tyrone yesterday.

The images of young men from the Gaelic Athletic Association and the Police Service of Northern Ireland standing side-by-side in salute to Ronan Kerr's short life should be imprinted on the minds of every person who votes in the forthcoming elections on May 5.

The people voted overwhelmingly in their tears and with their feet yesterday behind his coffin to reject terrorism and support peaceful partnership.

Constable Kerr's funeral demonstrated that the PSNI has the support and commitment of Catholic and Protestant alike. Regrettably, as a senior PSNI officer reminded us later, it will take more than sympathy and condemnation to isolate totally those who killed the police officer and who plan to continue their senseless terrorism.

The discovery of a significant arms and explosive cache in east Tyrone will be greeted with relief. This was a store of death aimed at destabilising the vastly improving political climate and bringing more anguish to families.

As the emotions of this week subside, the PSNI is left with a battle on its hands. Dissidents may be numbered only in hundreds, but they pose a worrying threat to the lives of other officers.

Their murderous activities show that they have the capacity to cause more death and destruction unless they are ostracised as never before from the neighbourhoods in which they hide.

Political, social and church leaders in the republican community must bring their influence to bear, particularly on would-be young recruits. If anyone has even the slightest grain of information about such activity, then now is the moment to act. As Cardinal Sean Brady said yesterday: "Stop now."

A concerted campaign to persuade dissidents of the pointlessness of their actions needs to be waged on a variety of fronts - not least through overt and covert police operations. The cross-community support shown for the PSNI this week must translate into improved information-gathering, north and south.

The presence at yesterday's funeral of the new Taoiseach, Enda Kenny, was therefore significant. Cross-border cooperation and total commitment between the Garda and PSNI is essential.

The terrorists are not beaten, but they have won nothing other than the scorn of the society they claim to serve. As Peter Robinson said, terrorism is uniting this community rather than dividing it.

We must all hope that the events of this week will mark the beginning of the end, but wishful thinking is no substitute for hard evidence.

What is evident is that Northern Ireland is closer to a better future than it was this time last week. That is Constable Ronan Kerr's lasting legacy to us.