O'Callaghan did a very unusual thing: freely admitting guilt

There were leading journalists and politicians present, there were diplomats and academics, there were lawyers and military and policing figures.

Writers and government ministers also went to St Martin in the Fields in central London to pay their respects.

No-one was under any illusion about what O’Callaghan had done – murdering two people for the Provisional IRA.

But what he then went on to do was extraordinary, and very unusual. After making up an excuse to leave the IRA he returned and became very senior in the terror group in the Republic of Ireland, but secretly worked on behalf of the garda.

The murders were haunting him.

Later, in the 1980s, having left the IRA altogether he walked into a police station in England and confessed his guilt.

More than 3,000 people were murdered by terrorists. O’Callaghan was not the only one to feel guilt and remorse: it is likely that there are many men and women whose lives have been wrecked by the recollection of what they did.

But it is one thing to feel such remorse, and quite another to voluntarily admit it, and forfeit your liberty.

He was freed in the late 1990s, and put his time to good use, making contact with influential friends, as evident yesterday.

He also, along with Shane Paul O’Doherty and others was a crucial counterbalance to IRA lies and victimhood — a remorse-free zone that is facilitated by no shortage of naive people who were not themselves IRA supporters but who fall for fake displays of goodwill by sectarian terrorists.

In a letter, right, Emma Little-Pengelly MP calls out Mairtin O’Muilleoir on the latest republican claim of collusion.

The wide definition of collusion, indulged far too long by London, makes the IRA look like a noble response to the state.

O’Callaghan and O’Doherty and others give us a much clearer idea of sectarian motives behind republican murders.