If Bertie Ahern had gone public with his threat to revive the Republic’s constitutional claim over Northern Ireland it would have provoked a major crisis in Anglo-Irish relations as well as the peace process.

The hardball tactic was intended to test Ian Paisley’s resolve. As the Irish government saw it, the DUP leader was attempting to have his cake and eat it.

His party had rejected the Good Friday Agreement and was publicly refusing to fulfil its terms by sharing power with Sinn Fein, the largest nationalist party. At the same time it was intent on pocketing the major unionist gain from the Agreement — the removal of Articles 2 and 3 of the Irish constitution.

Article 2 specified that “the national territory consists of the whole island of Ireland, its islands and the territorial seas”.

Even though Article 3 specified that until the territory was re-integrated laws passed in the Dail should apply in the 26 counties, the provision was a major irritant in north/south and Anglo-Irish relations.

The territorial dispute made a visit by the Queen to the Republic or the Irish president to Northern Ireland or Britain diplomatically impossible.

It was also seen by armed republicans as justification for violence and by unionists as proof of the Republic’s aggressive intent.

It was removed in 1998 as part of a referendum to ratify the Good Friday Agreement, a package deal. The package voted on also involved power-sharing and a consultative role for the Republic in Northern Ireland as a guarantor of nationalist rights.

Premiers Bertie Ahern and Tony Blair had already agreed to “churn the process in order to keep Ian Paisley’s DUP party on edge”. This involved ratcheting up north-south meetings and cross-border co-operation.

This pressure helped wear Paisley down. He later admitted that one of the factors which induced him to reach agreement was fear of joint Dublin/London rule without unionist input.

Mr Ahern increased the pressure by “giving a speech in which he reminded people that the Republic of Ireland had changed its constitution to relinquish its claim to Northern Ireland only on the basis of the promise of the Good Friday Agreement”. He told the Americans if that promise is not met he “would indicate that Ireland could consider changing its constitution again”.

Would the threat of a new referendum to restore the hated articles have worked even quicker?

It is arguable that the slow build-up to a referendum would have moved Paisley.

Or he might have been toppled by more pragmatic forces if he dug his heels in and refused to negotiate. Or the peace process might have been brought to a juddering halt.

We shall never know. Bertie Ahern, cautious and pragmatic to the last, decided not to go for the nuclear option — but he got his way just the same.

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