Washington: The shamrock had been presented, the speeches made and the Taoiseach was about to leave the White House to brief the press when the security lockdown began.
A man had climbed over a fence into the White House grounds and was arrested immediately but the security staff were taking no chances.
"We've got a jumper," a guard shouted as he ordered waiting cameramen and reporters off the grounds.
The Irish media were ushered out of the driving rain into a nearby office building as officials tried to contact the Taoiseach's entourage.
The Secret Service was ordering the Taoiseach's party into cars to drive to Andrews Air Force base when president George Bush heard that Mr Ahern was going to miss his own press briefing.
"Make it happen," the president told officials and within minutes the Taoiseach and the media enjoyed a happy reunion.
It was a dramatic end to a subdued St Patrick's week in Washington that was dominated by the approach of the March 26th deadline for forming a new executive in the North.
Neither Gerry Adams nor Ian Paisley was in Washington, although Martin McGuinness and Ian Paisley jnr both attended yesterday's White House reception. Relatives of four murder victims - Pat Finucane, Joseph Rafferty, Raymond McCord and Robert McCartney - were there too, a reminder of the darkness from which the North is emerging.
Ireland is the only country in the world whose leader is guaranteed a meeting with the US president at least once a year and after 10 years in office, the Taoiseach could do the symbolic part of the programme in his sleep.
His speech at Irish Ambassador Noel Fahey's party on Thursday was a masterpiece of self-deprecating humour, gentle flattery and quiet advocacy. The party attracted so many of Washington's most powerful people that there were enough secret service agents to have a party of their own.
Chief Justice John Roberts and Supreme Court Justice Antonin Scalia were there, along with so many senators and congressmen that Mr Ahern didn't even name them individually in his speech.
At the speaker's lunch earlier that day, hosted by House speaker Nancy Pelosi and attended by the president, even the music was provided by a political heavyweight. Maryland governor Martin O'Malley sang The Star-Spangled Banner, followed - in Irish - by Amhrán na bhFiann.
The British ambassador hosted a lunch at his residence yesterday in honour of Northern Secretary Peter Hain, which representatives of almost all the North's party's attended, although Sinn Féin were unable to make it. Dublin City University used its powerful network of Washington contacts to host a party to advertise its science and technology prowess.
Perhaps the most telling event of the week was the Northern Ireland Bureau's breakfast on Thursday to launch Rediscover Northern Ireland, a festival promoting the North's cultural, educational and economic transformation that will run for months in Washington. An exhibition of photographs from the past 40 years showed in the most compelling way where the North has come from in recent years and where it just might be going.