Key quickly retorted, "I've gone off Ferraris because they look best in red".
Behind the political repartee there was a serious point. Cullen had got public debt down and wanted to keep a tight hold on the Government's purse strings.
It was his second Mood breakfast.
In 2004, he had squared off with Don Brash who was then National's shadow finance minister. Brash was a former Governor of the Reserve Bank who also knew his stuff.
The boardroom was never really Cullen's milieu. But they applauded him that year, for negotiating with Australia to form a single economic market (SEM) with New Zealand.
By 2006, Key was National's leader and Sir Bill English shadow finance minister. The final election debate between Cullen and English took place in 2008 in the midst of the Global Financial Crisis.
As the Herald reported, the two men vying to be Finance Minister through looming hard times, confronted each other at breakfast but neither really emerged a clear winner in one of their last campaign battles.
Cullen and English both strongly defended their policy plans. Cullen had a parting shot to make.
"This is no time for the financial top end of town to be giving one-sided lectures to governments around the world ... at a time when the Gordon Gekkos of the world are being propped up and often taken over by the Gordon Browns of the world."
It was no surprise Key called Cullen up to his office to sound him out for jobs after Labour's defeat. Beneath the politicking, National had deep respect for his abilities.
In a tribute after his death, now-Finance Minister Grant Robertson said Cullen had made an enormous contribution to "long-term economic prosperity and stability".
"As architect of KiwiSaver, the Super Fund and Working For Families he has left behind an economically more secure country.
His contribution to Mood of the Boardroom over the years was deeply appreciated. He leaves a vacuum in our national conversation.
So, to 2021
The Herald's Mood of the Boardroom 2021 CEOs Survey attracted participation from 151 respondents. This year, 130 chief executives and 21 senior directors or chairs took part.
The survey went out to CEOs just prior to the August 17, level 4 lockdown.
The survey stayed in market for six weeks to capture the views of as many chief executives as possible given the challenges they faced operating businesses under Covid.
The Herald survey is conducted in association with BusinessNZ.
BusinessNZ also put 15 questions from the survey to its SME membership. The results are on B34-35 of this report.
The Herald hopes to host the Mood of the Boardroom debate between Robertson and his National opponent Andrew Bayly later this year.
Finally a huge thank you to everyone who took part, including also the Herald Reports team, which has with great goodwill produced the 2021 report.
Fran O'Sullivan Executive Editor Mood of the Boardroom
A headline in the Mood of the Boardroom print liftout edition was incorrect. Sir Michael Cullen was born in 1945, not 2045. The liftout was printed before the error was seen. We regret the error.