Christy Moore sang 'An Ordinary Man' for trucker Joe McNamara -- the man who drove a cement lorry up to the gates of Leinster House with the words 'Anglo' and 'toxic bank' on the side -- while up to 50,000 people marched in Dublin against Government austerity measures and the intervention by the IMF.
Bottles and missiles were later thrown at a breakaway demonstration outside the Dail, but nobody was injured and no arrests were made.
Around 50,000 people braved the intense cold to march from Dublin's Wood Quay to the GPO to show their disgust at spending cuts and tax increases by the Government in a protest organised by the Irish Congress of Trade Unions (Ictu).
After an hour of speeches, music and song at the GPO they heard the crunch line from Ictu general secretary David Begg, who said nobody could believe that the country could afford the 6.7 per cent interest to pay for money that Ireland did not want to bail out the banks.
Referring to the rate that was initially mooted for the €85bn IMF and EU loans, Mr Begg said:"We cannot pay that money, we will not pay that money."
Calling the march a powerful message to Dail Eireann, he said the IMF had come bearing weapons of economic mass destruction.
He quipped that at least " Dick Turpin had the decency to wear a mask".
On the Government, Mr Begg said: "They must not under any circumstances accede to the terms of this Versailles Treaty."
Siptu and Ictu president Jack O'Connor said people had turned out to assert the rights of the citizens of Ireland to decide the future of their country.
Mr O' Connor said they objected to the arrogance of the Government who did not retain the support of the people, even remotely, saying they had brought the country to a shameful place.
It had been reported that the IMF was on a rescue mission but it was a rescue mission on behalf of the people at the top of the banks in France and Germany, according to Mr O'Connor.
And he said that it appeared the Government did not intend to go away and they had brought in an old-fashioned, right-wing, four-year plan devoid of imagination and with not a single word devoted to the contribution our tax exiles could make.
Instead, the Government was trying to fix the problem by cutting the national minimum wage of the most vulnerable in the country.
Writer and journalist Fintan O'Toole also spoke of the "savage assault" on the minimum wage by the Government and he said that cuts in social welfare would further impoverish people who were struggling to survive.
Criticising the four-year plan, he said it was a plan to save the "Irish elite".
He told the marchers that they had gathered outside the GPO to reclaim a sense of citizenship. He said that as the fate of our country was being decided, it was a case of "mind over matter".
"They don't mind, and we don't matter. Our rulers have no shame, and they believe we have no voice," said Mr O'Toole.
In an impassioned speech, he told protesters: "We are not subjects, we are citizens, and we want our Republic back."
One speaker, pensioner Marie Doyle of the Retired Workers Committee, said that they lived in fear of December 7.
"We resent being told we are a burden on the State.
"We have paid for our pensions, we are not parasites," she said.
Ms Doyle said pensioners were living on the edge of poverty, adding: "It's morally unacceptable that any government would treat vulnerable people in this way."
Nearby, a new left-wing grouping held their own meeting in O'Connell Street, opposite Burger King.
Socialist MEP Joe Higgins called for a 24-hour general strike until the" disastrous" policy of "supping with the IMF" was stopped.
Mr Higgins said trade union leaders didn't know how to fight and urged grass roots trade unionists to take charge of their unions, pledging: "There is no way that a penny will be paid to the IMF."
Mr Higgins' colleague, Dun Laoghaire councillor Richard Boyd Barrett of the People Before Profit group, called on people to lay siege to the Dail on Budget day.
Later, there was a tense stand-off outside the Dail between gardai and around 250 protesters.
About half a dozen bottles, paint bombs, snowballs, and other missiles were thrown at gardai guarding the front of Leinster House on Kildare Street as a poster of Brian Cowen, dating back to the Lisbon Treaty campaign, was burned. None of the bottles hit gardai and there were no injuries or arrests.
The protesters included members of the Socialist Workers Party and other left-wing groups, Sinn Fein supporters and members of the Republican splinter group Eirigi.
After about an hour gardai moved in and broke up the protest and the crowd dispersed.