Whatever their mandate, it is hard to see how the republican movement can be candidates for executive office in Northern Ireland or government in the republic for the foreseeable future. Putting Sinn Fein in power, north or south, would create a tin-pot state in which criminals had the politicians in their pockets.

Forget the planning scams and brown envelopes that have been the stuff of political corruption in the south. Forget even the discrimination in housing or job allocations that blighted northern politics for so long. This would be a society in which a party linked to robbery and cigarette smuggling would hold ministries such as justice, security and health. A society in which senior politicians would defend the criminals against the police, as Martin McGuinness did when he rounded on Hugh Orde, the PSNI chief constable, and backed the IRA at a press conference on Friday.

Republicans have lied through their teeth to both governments, other political parties, and the electorate in the past week. Their credibility is now undermined to the extent that nobody but a fool would take anything they say on trust.

In republican areas, there is even less doubt than there is at police headquarters that the Provos carried out the Northern Bank robbery. Asked about the IRA denial one former republican prisoner quipped that the first name of P O’Neill, the name at the end of IRA statements, was Pinocchio and that his nose grew a little longer last week.

The IRA’s denial followed in the organisation’s long tradition of lying when in a tight corner. The full list is tedious but in the past the IRA denied the Birmingham bombs, the Castlereagh break-in, the murder of Jerry McCabe, smuggling weapons from Florida, any links with the Colombia Three and, most shamefully of all, responsibility for “disappearing” Jean McConville and other people it murdered and buried.

In many cases the IRA admitted, years later, that it had lied. In others it maintained the fiction. The choice of which line to take was purely one of political expediency.

Republicans say the police and the British government, the “securocrats” as they call them, are out to wreck the peace process, to exclude them, and to return us to conflict. Orde is accused of anti-republican bias and of demonising Sinn Fein.

The reality is that Orde is determined to the point of obsession to win Sinn Fein’s support for the PSNI and to coax them onto the police board. As operational head of the Stevens inquiry, he tried to root out collusion between British security forces and loyalists. Since he took over as head of the PSNI, most senior Special Branch officers have taken redundancy, often amid bitter recriminations.

A south of England technocrat, Orde has no commitment to Northern Ireland politics. He has made no secret of his desire to get Sinn Fein involved in policing and wants young people from republican areas to join. Only last month Gerry Adams and McGuinness went to Downing Street to meet Orde and discuss a rundown of military and police installations in the province. They said the meeting was useful.

So the last thing Orde wanted to do in his first television appearance of the new year was to stand up and, effectively, call Sinn Fein liars. Yet he had to if he was to retain credibility.

Tony Blair also has a vested interest in doing business with Sinn Fein. He desperately wanted power sharing and the beginning of the end of the IRA in time for the next British general election and he was prepared to give them almost anything in return. Blair had invested political capital in doing a deal and now finds himself looking foolish.

Bertie Ahern is also embarrassed. This robbery was being planned as he negotiated with Sinn Fein in good faith and listened to their assurance about the running-down of the IRA.

It had “obviously been planned at a stage when I was in negotiations with those that would know the leadership of the Provisional movement”, he observed.

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