"I think it will be just a pleasant dinner. It's an opportunity to talk to a few people about a few issues."
However, it will not all be pleasure.
"I'd like to talk to the odd one about the big crisis facing New Zealand with the welfare system, which is getting far too costly. I know National won't do anything about it so I'm hoping Labour will."
United Future leader Peter Dunne will also be there and kicked off the fireworks early by penning a critique of the modern day Labour Party compared to Labour of the past, including the "reforming and innovative" fourth Labour Government he was part of. In it he said Labour had lost its soul and place and was too negative.
Current leader Andrew Little responded in kind, pointing out Dunne was a "party of one".
After that prelude to the big night, when asked what the diners would be eating Mr Nash quipped "each other" with a grin before listing a far more prosaic menu of canapes, lamb rump and chicken breasts.
He was pleased former MPs from across the board had opted to attend and was not expecting bad behaviour, despite the mix.
"None at all," he said. "These are all grown men and women who know how to behave in a public setting."
While he did not agree with Mr Dunne's analysis, he said he was glad Mr Dunne had decided to come along. Every current and former Labour MP was invited, regardless of their fate.
"There were some who were expelled from the party, there were some who left the party. People who started as Labour MPs didn't necessarily finish as a Labour MP but we are a broad church. It's a celebration of everything that is great about Labour."
Other attendees include Sir Geoffrey Palmer who took over as Prime Minister after Lange resigned and Bob Tizard - a minister in both the Norman Kirk and David Lange governments. Mr Tizard's daughter Judith Tizard, who was a minister in the Helen Clark governments from 1999 to 2008, will also attend.
Mr Little will speak at the event, but measures have been taken to ensure Labour does not gloss over its own history: the main entertainment will be a panel of longstanding former and current Press Gallery journalists Linda Clark, Jane Clifton, Barry Soper and Tom Scott.
Both Sir Roger and Mr Bassett were also in Parliament for Norm Kirk's third Labour Government from 1972 to 1975. Sir Roger left Parliament in 1990 and went on to found the Act Party in 1993. He returned to Parliament as an Act MP from 2008 to 2011 before retiring.