Prime Minister John Key has announced the possible return of a gay and lesbian mardi gras-style festival - 10 years after a lack of funding led to the end of Auckland's Hero Parade.

Mr Key made the announcement at yesterday's Big Gay Out in Pt Chevalier, where he was joined by Auckland Central MP Nikki Kaye, who said the Government, council and tourism council-controlled organisations still had to calculate the economic feasibility of an annual event similar to Sydney's Gay and Lesbian Mardi Gras.

She said the festival would be a departure from the Hero Parade, which ran from 1992 to 2001 before it was cancelled as a result of mounting debts.

Ms Kaye said she thought there was "a really good economic case" for a new mardi gras-style festival.

"But also the main aim has to be to celebrate the gay and lesbian community and have greater visibility in Auckland."

Mr Key's announcement was met with applause and cheers by the 10,000-strong crowd that descended on Coyle Park to celebrate the country's largest rainbow festival.

However, he was pursued on the issue of the civil unions legislation, which he voted against when Labour pushed it through Parliament.

The PM said the Government had been true to its word in not rolling back any of the gains made by the gay, lesbian, bisexual and transgender community, including the Civil Unions Act.

Radio host Steven Oats invited Mr Key to his stall and asked him whether he would support civil unions if a conscience vote were held tomorrow.

"I voted against it last time. It was a very marginal call. But we're not going to face that again, so ..."

Mr Oats persisted, but Mr Key would not reveal his cards.

"I'm leaving it until my book. I know the answer, but just wait until my book," he said.

The Big Gay Out also raised money for Northland lesbian couple Lindsay Curnow and Juliet Leigh, who lost tens of thousands of dollars when their small flower business was torched and destroyed in an apparent anti-gay attack last month.

A week before the fire, the couple's house, cars and shed were defaced with abusive anti-gay messages.

Big Gay Out organiser Dawn O'Connor said the crowd was well behaved and drank responsibly as temperatures reached 27C.

Ms O'Connor said the dance tent, complete with chandeliers and rugs as well as a 10m water slide, was among the most popular attractions.

TVNZ presenter Alison Mau, a long-time supporter of rainbow community events, made a surprise appearance on stage and introduced Mr Key.

Mau has been strongly supported by the gay community since she came out as bisexual at an HIV fundraising event in Auckland late last year.

Mr Key's appearance at the Big Gay Out follows his debut on the catwalk at the launch of the Rugby World Cup volunteers' uniforms two weeks ago, when he sashayed his way along it before asking host and fellow Cabinet minister Murray McCully, "Do I look hot?"

The Prime Minister later said on TVNZ's Breakfast show that his catwalk behaviour had been "stupid".

"I shouldn't have responded to the crowd saying that, I shouldn't have done that.

"But on the other side of the coin, there is a very serious message of what we are trying to do here for New Zealand and there is a balance in my job."

In 2001, continuing controversy crippled the Hero Charitable Trust's efforts to find sponsors for the annual Hero Parade, considered to be the showpiece for the gay community.

Trustees announced they were $142,000 in debt and confirmed contractors had not been paid for cleaning and fencing services for the parade 10 months earlier.