"Frictionless movement was part of a strategy of "normalisation" of relations between Protestant and Catholic communities within Northern Ireland and across the border", the Institute for Government said, with the government calling it "the most tangible symbol of the Peace Process". The Good Friday accords ended seven hundred years of conflict.
"I've never come across a time when there's been so many experts on the Good Friday Agreement, and yet most of the people who're spouting about it weren't within a mile of it".
"First of all it is very hard to pass a trade bill in the Congress of the United States, so it's no given any way", she told her audience.
She repeated the message on arrival in Dublin yesterday, saying a future US-UK trade deal was "just not in the cards" if there was any damage from Brexit to the 1998 agreement.
"It was a model and other people have used it as a model and we don't want that model to be something that can be bargained away in another agreement".
In short, Mrs Pelosi's position seems to be the United Kingdom should do what the Republic's government wants, or forfeit a trade deal - a position Lord Empey likened to "an attempt to blackmail people".
Pelosi's remarks served to bolster demands by the European Union that any agreement allowing for Britain's orderly departure from the bloc must guarantee that the border between Northern Ireland, a part of the United Kingdom, and the Republic of Ireland, a member state of the European Union, remains as it is now - open and virtually invisible. What's being discussed? "Brexit, Brexit, Brexit", she said.
Media captionWho is Nancy Pelosi?
Pelosi, Speaker of the U.S. House of Representatives, was speaking at the London School of Economics ahead of her planned visit to Dublin where she today met Taoiseach Leo Varadkar and Tánaiste Simon Coveney.
Wednesday marks the 100th anniversary of the Dáil (lower house of the Irish parliament).
The President Michael D Higgins will host a working meeting for the delegation tomorrow.
On Wednesday, Pelosi and the delegation - which includes members of the Friends of Ireland caucus - will be honoured at a dinner in Dublin Castle, the former seat of British power in the country.
Following the Brexit extension, US President Donald Trump issued a threat to shake-up America's trading relationship with the EU.