The problem with his flag scheme was he was the one hoisting it up the pole. It had an air of personal whim about it. If it didn't start as a vanity project, it became one ... it also developed into a political battle.
A desire to change the flag, and other similar symbolic gestures, should come from the grass roots up, not from the top down.
One sensed he wanted it to be his legacy, and one worries when leaders of nations turn their thoughts to leaving a legacy.
By many accounts he ran the country effectively and efficiently for eight years. He did his job. Isn't that enough? Does there have to be a "legacy"?
The leader's legacy theme is very American and if we think of US presidents and what they have left behind, we can quietly shudder. Enhanced interrogation, aka torture, on innocent people at places like Guantanamo Bay; soldiers and civilians still mired in unending wars in far-off fields and so on.
In the interview, Sir John admits it was "not the most important issue by a long way for the country". And yet he put it centre stage.
He says it didn't pass because Labour and the Greens turned it into a political issue, but he made it political with his unequivocal endorsement.
He says he "should have pushed it even harder". But, in fact, he should have stepped well back and let popular groundswell carry it onward ... or not.
And he doesn't mention regretting the $20 million-plus spent on the whole charade.