In an oddity of the tournament, the New Zealand team were unbeaten in games against Wales, France and Argentina, but Australia racked up a better points differential and were crowned world champions.
"We got jacked up and we will make sure that that doesn't happen again," Mr Peters said.
"They changed the rules before we came to the first meeting, and nobody could protest about the change."
Mr Peters was in England as the team's media manager. He defended not putting out any press releases.
"What I did was make sure I kept them away from the prying eyes of people like you [reporters]."
The tournament happens prior to each Rugby World Cup, and the trip was funded through sponsorship, including from Air New Zealand, with players also dipping into their own pockets.
Corrections Minister Sam Lotu-Iiga was down to attend, but decided to stay in the country as the controversy over Serco-run Mt Eden prison rumbled on.
This year the team was made up of the eight MPs, as well as a core of Parliamentary staff and family, including former All Black Ofisa Junior Tonu'u and former Japanese international Jack Tarrant.
The Parliamentary Rugby World Cup takes place prior to the real tournament every four years, in the same host country.
It was established in 1995, where a New Zealand team including Bill English, Murray McCully, Mr O'Connor and Trevor Mallard won.
Competing Parliaments this year were New Zealand, Argentina, Australia, France, Ireland, Japan, Scotland, South Africa, the United Kingdom and Wales.
