"I think we have better outcome by way of law and diversity within Parliament."
Asked if he was doing anything to celebrate his 25-year anniversary, he said he would be having a "cup of tea" with Ruth Dyson.
Dyson – a former Labour Party President – said a lot had changed over the past quarter century.
"The diversity and the way of doing politics has changed significantly. MMP has driven that change and I think it's really great."
The fact that a single party cannot dominate the decision making is a great change, she said.
Parliament is now a much more inclusive place, she said.
Under the previous Labour Government, Dyson held a number of ministerial roles, including Social Development.
"My favourite thing was getting the New Zealand sign language bill passed as an act, making New Zealand sign language an official language."
Asked if she would stay around for another 25 years, Dyson said she feels "passionate, energetic and I love the job. If I didn't, I would know it would be time to get out."
Dyson entered Parliament after winning the Christchurch electorate of Lyttelton.
She beat National's David Carter – who entered Parliament a year later in a byelection. He was the Speaker of the House in the last Government.
He today congratulated them for their feat.
He said he had a "very good relationship" with both MPs.
"I have signalled that I will be leaving at the end of this term, that will be 26 years and that will be long enough for me."
He said it's for Dyson and O'Connor to decide how long they "stick around for".
Both MPs were greeted by applause when they walked into Labour's morning caucus meeting.
The only other MP to serve a longer, continuous stint in Parliament is National's Nick Smith.
Both Winston Peters and Speaker Trevor Mallard have been around for longer, but have both been out of Parliament for periods of time.
