Former Prime Minister Helen Clark favours a simple Southern Cross flag as a new New Zealand flag.

"If we took the Union Jack out of the corner, the flag with the Southern Cross, I think, is very nice," she said during her visit this week.

She also thought the flag by artist Dick Frizzell - also featuring the Southern Cross - was "rather nice ... that's the concept I quite like."

But she does not believe the flag should be changed without long and careful consideration.

Helen Clark said she sought advice in 2004 when businessman Lloyd Morrison was trying to collect signatures for a citizens-initiated referendum on changing the flag.

"The strong advice was you would need to go through a really long and proper deliberative process.

"You can't just change a symbol of nationhood that people have fought under, played under, lived under without a long, thorough debate and building a public consensus, so it is quite a long process you would have gone through."

When the petition failed to get enough signatures, it wasn't important enough to push to the fore, she said.

Helen Clark was advised in September 2004 that a referendum could have been held with the 2005 September election if 240,000 signatures had had been submitted for checking by May 2005.

By July, Mr Morrison and his change-the-flag supporters had only 100,000 signatures, so they stopped collecting.

The advice given to Helen Clark was from former Cabinet Secretary Diane Morcom, and the chief executive of the Culture and Heritage Ministry.

Released this week by the Department of the Prime Minister and Cabinet, it advised Helen Clark that the Government should not lead the initial stage of the process - public debate about whether to change the flag.

But if it was established that there was wide support to change the flag, the Government should get involved to ensure that the process for change succeeded. If it didn't succeed it could damage the flag as a unifying symbol.

The paper to Helen Clark said a change to the flag would require a higher level of public awareness and participation than for example the review of the honours system in 1995 "because of the special status of the flag as symbol of New Zealand's identity".

It suggested that once the level of public support had been established, a process for change, facilitated by the Government could involve public consultation on process, multi-party support, an information campaign, a design component consultation with experts; and decision-making components involving public participation.

Official advice to Helen Clark on the flag in 2004

* "Because of the importance of the flag as symbol of New Zealand's identity, the Government should not lead the initial stage of the process.
* "If a process for change were to be initiated, it would be important that it succeeded, and resulted in the adoption of a new flag.
* "If the process failed, it could damage the flag's status as a unifying symbol, and there would be a risk that the issue would not be revisited against for a long time."
* "It would be desirable for change to be widely supported by other political parties. This would ensure the process remains apolitical and would allow it to run across different administrations, if necessary."