Former National Party leader Dr Don Brash has given the previous National Government led by John Key a shocking 0/10 rating, which Duncan Garner says is "too harsh".

Dr Brash told The AM Show on Tuesday the previous Government "failed most of the things they said they'd do".

"When John Key became Prime Minister he said we'll catch Australia in 17 years by 2025," he said, adding that this never happened, and that the former Government failed on housing affordability and growth.

Addressing the current Government's situation, Dr Brash said teachers are "grossly underpaid" and said he thinks "bad teachers are probably overpaid".

He said incomes per head in New Zealand have not been growing in the last 15 years and teaching is among the many professions feeling the financial pinch. The former Reserve Bank Governor said teachers are up against rising house prices and that "life is tough".

Dr Brash said he was shocked to be nominated for the KiwiBank New Zealander of the Year award for 2019. Dr Brash is named by the award organisers as a former National Party leader and "free speech advocate".

"There are people who are much more worthy," he said, suggesting AUT professor Paul Moon as a "much more worthy recipient of the award" for initiating a petition on free speech last year. The professor wrote an open letter calling for the defence of freedom of speech on university campuses.

Dr Brash himself has defended free speech. On Friday he took part in a free speech debate on whether "PC culture" had gone too far, hosted by the Auckland University Debating Society.

It was organised after the cancellation of a Massey University event which was cancelled due to concerns about potential violence. At the AU event, a group of protestors heckled Dr Brash during his speech, while a group of supporters chanted his name in the lecture hall.

Dr Brash said was "utterly astonishing" that the Massey event was cancelled.

As well as being an outspoken supporter of free speech, Dr Brash has also openly criticised the current and previous Government.

The former MP reflected on ex-BNZ chairman Kerry McDonald who in the past has rated former Prime Minister Helen Clark's Government as 2/10 and the John Key/Bill English Government 0/10.

Dr Brash said he agrees with Mr McDonald's rating.

But The AM Show host Duncan Garner said a 0/10 rating for the former Government is "too brutal and too harsh".

Garner said the previous Government deserves 10 points for its handling of the 2008 financial crisis and the 2011 Christchurch earthquake. He said $50 billion was borrowed "because they had to keep the benefits flowing".

However, he said the previous Government "forgot about ordinary people struggling" near the end of its term, and that John Key and Bill English forgot how difficult it can be for middle class families trying to get by.

Newshub.