Prime Minister Bill English says his past opposition to civil unions and gay marriage was not the reason he didn't speak at the Big Gay Out in Auckland yesterday.

Mr English's predecessor John Key made a speech at the event each year. Mr English said he did not think it was a big issue that he had not done so and didn't see a reason to speak. He left speaking duties to his deputy, Paula Bennett, at the event yesterday.

Mr English said if people were enjoying themselves at community events there was no need to be political.

Mr English had in the past opposed bills supporting gay marriage and civil unions, but has since said he's changed his mind on the issue and he saw no reason to change the law now that gay marriage was legal.

"As I explained yesterday, time's passed, the legislation's gone through, people are getting on with their lives," he told Susie Ferguson on Morning Report today.

"It seems to be working fine, it doesn't affect other people's marriages and so there's no reason to change it."

He said he took his time to change his mind on the issue because he was socially conservative.

"I've always been, I think, openly conservative about all these issues. Change can be threatening, I think you should always be sceptical about social change and I was."

He said that didn't mean he had thought gay marriage was a threat, and he did not consider it to be a moral issue.

"It's not necessarily an issue around morals, not the way I saw it anyway."

"Time's passed, it's worked. People are getting married and as I said I don't see any particular reason to change it."