Peace was never meant to be like this. Seven years after the Good Friday agreement, the organisation that had killed and terrorised in the name of Irish republicanism stands accused of a brazen, multimillion-pound bank robbery and a full range of less spectacular but still lucrative criminal activities. As we report today, police now rank the IRA as Europe’s biggest organised crime gang. It is certainly sophisticated and money-generating. Not content with apparently masterminding the £26 million Northern Bank raid in December, it also distributes counterfeit brand-name vodka indistinguishable from the real thing — and that is even after the legitimate manufacturer introduced a new and secret seven-stage filtration process.

The immediate price of the Good Friday agreement for London and Dublin was the heavy moral compromise implicit in the early release of IRA prisoners serving time for terrorist offences. To this must now be added the financial cost of police and intelligence operations against what amounts to a northern mafia, and the political price of a slap in the face from individuals whom both governments have had to take at their sullied word.

Gerry Adams and Martin McGuinness were engaged in intense negotiations with Bertie Ahern, the Irish Prime Minister, even as the IRA was almost certainly planning the astonishingly bold raid that the Taoiseach insists both Sinn Fein leaders must have known of in advance. His sense of betrayal over that raid is behind his Government’s recent series of disclosures of IRA criminality, and his demand this week that IRA members step forward to solve the appalling murder of Robert McCartney. Such disclosures, however, may seem to make a retrospective mockery of a peace process that last November appeared close to a breakthrough on arms decommissioning, which fell apart after bickering over photographic evidence.

There is now no question that the IRA has exploited the calm brought by the Good Friday agreement to diversify into organised crime on a scale to make Al Capone blush. But a return to violence is not imminent; the Irish peoples’ desire for peace is not so fragile, nor so easily mocked. On a purely practical level, moonshining and bank theft do less to deepen sectarian divides than continued bombings, even when accompanied by criminal intimidation. More importantly, the peace process has stripped the IRA of its political cover and exposed its rump membership, to republicans and Unionists alike, as unreconstructed gangsters and petty thugs. One result is the near-unamimous republican revulsion over Mr McCartney’s murder, and public displays of that disgust.

Such freedom from fear did not die with last year’s decommissioning proposals, and it must not be allowed to now. Mr Ahern and Tony Blair must insist on ever greater co-operation between their respective police and security forces in order to stamp out what remains of IRA intimidation. Its operatives will then have lost their main defence against arrest and prosecution not as freedom fighters, nor even as terrorists, but as common criminals. Mr McCartney’s sister, Paula, has called for his killers to face justice in the courts, not vengeance from vigilantes. Her plea must be answered, by any means available. Capone was eventually jailed for tax evasion, and incarceration awaits these modern-day boot- leggers and bully boys.