Sir John Key's knighthood won't shield him from calls to resign as ANZ's chairman, political commentator Bryce Edwards says.

In fact, the Victoria University academic says the honour only puts a larger target on the former Prime Minister's back.

On May 17, the Reserve Bank censured ANZ for "persistent failure" to properly calculate risk, and ordered to increase the amount of capital it holds as a safety net to absorb possible losses, by 60 per cent to $760 million.

In a letter to Reserve Bank governor Adrian Orr, former BNZ chairman Kerry McDonald said he was "amazed" at the limited penalty imposed on the bank and called for ANZ CEO David Hisco and Key to resign.

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ANZ says it regrets the error, but also that the sum involved was a small portion of its total capital and that it had "no impact on customers or the operation of the bank."

"I believe John Key is going to be under much more pressure had this occurred 10 or 15 years ago because there's so much more public appetite to hold the powerful to account," Edward says.

"Since the GFC, there's been a much greater emphasis on equality - not just economic, but inequality of power and anger about elites - and in particular bankers," Edwards says.

"So I don't think it's surprising that the calls for Key to resign are resonating widely. He'll be under a lot more pressure than if this had happened a decade ago.

"Some of it is partisan, but there's more to it than that. There's now a lot more suspicion about politicians who go into business and whether they'll be held to account," Edwards says.

"We really do live in an age of elitism - it's a worldwide phenomenon. The knighthood exacerbates his elite status and makes calls for his resignation even more strongly felt by many."

Dame Jenny Shipley's ongoing tussle with Mainzeal is another example of a Queen's honour being no protection in era of suspicion of elites, Edwards says.

For its part, ANZ is playing down the incident.

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"ANZ New Zealand does not believe there is a systemic failure in its controls and attestation processes," a spokesman said.

"We reported the issue to the RBNZ in April 2019 after an internal review showed we weren't using an approved model for the calculation of the bank's operational risk capital."

The calculation of ORC since December 2014 was based on a previous RBNZ-approved model - that was decommissioned without RBNZ approval- with an annual adjustment to reflect the growth of the bank's business, the spokesman said.

"The use of the ORC model meant that ANZ New Zealand was carrying about $23 million less in capital as at 31 March 2019 than it should have. This represents a very small proportion of the approximately $12.4 billion in total capital held by ANZ New Zealand at 31 March 2019. Regardless we have always been well above our minimum required capital levels as we carry significant buffers.

"The ORC model is one of more than 45 ANZ New Zealand models approved by the RBNZ to calculate capital under the conditions of the organisation's banking licence.

"While isolated, and with no impact on customers or the operation of the bank, ANZ New Zealand is disappointed this error occurred.

"Mr McDonald is welcome to discuss the issue with us at any time."