Former National Party leader Don Brash has not read or watched the work of Stefan Molyneux and Lauren Southern, but believes in their right to free speech.

Don Brash's son has attacked the upcoming legal action against Auckland Council his father is involved in, over the barring of two controversial far-right speakers from using a publicly owned venue.

In a battle of Brashs, Alan Brash has taken to social media to call the court action by Free Speech Coalition "a terrible idea and appalling waste of time and money".

Meanwhile, Taxpayers' Union chief executive Jordan Williams, having secured Don Brash's support, has emerged as one the main drivers behind the proceedings. The union has taken multiple shots at Goff since the start of his first term as mayor.

The Free Speech Coalition has successfully raised $50,000 needed for the court action – a judicial review of Auckland Live's decision to cancel a venue booking for Canadian speakers Stefan Molyneux and Lauren Southern.

The Coalition has found support from across the political spectrum, uniting lawyers, academics and ex-politicians. Prominent left-wing commentator Chris Trotter is one Coalition supporter.

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JASON DORDAY/STUFF Auckland Mayor Phil Goff tweeted: "Venues shouldn't be used to stir up ethnic or religious tensions."

On Wednesday, Brash said he had not read or viewed any of the controversial pair's comments, however, he believed in their right to express them.

"So I'm not defending what they're saying," Brash said.

"People are free to say whatever they want to say subject to not inciting violence – people are not allowed to incite violence under the law and that's entirely appropriate, but to the best of my knowledge they're not inciting violence."

SUPPLIED Canadian speakers Stefan Molyneux and Lauren Southern want be speaking at Takapuna's Bruce Mason Theatre as previously planned.

But Alan Brash, responding on Monday to his father's Facebook post about the fundraising effort, disagreed strongly with the legal action.

"This is a terrible idea and appalling waste of time and money," he wrote.

"Alt-right speakers frequently cite inflammatory rhetoric, often devoid of any factual basis to whip-up white resentment.

"I don't want any council-run premises doing *anything* to make it easier for them to spread their divisive BS - BS that causes actual harm to actual people [sic].

"It's the same if people cite lies to support an anti-vaccine argument: if you can't engage honestly and respectfully in discussion, then don't expect to be welcomed with open arms."

Brash Sr told Stuff he threw his support behind the legal action following a call from Williams.

WIlliams' Taxpayers' Union had been critical of Goff on numerous occasions since his election.

"Jordan did ring me and said 'what do you think about this'?" Brash said.

CAMERON BURNELL/STUFF Taxpayers' Union boss Jordan Williams, a key player in the legal action against Auckland Council, secured Brash's support.

"I must confess I hadn't really focussed on it much at all at that point, but the more he talked about it, the more I thought this was a serious issue," Brash said.

With the money now raised for court action, the next steps involve engaging lawyers and pushing ahead with the proceedings, Brash said.

"I'm certainly not defending in any way what they say, because I literally don't know," he said.

"People describe them as alt-Right, and I assume that's the case, but I don't know that from first hand.

"As I understand it they're certainly not advocating violence, because if they are that of course puts them beyond the law."

Auckland Live director Robbie Macrae last week said security concerns around "the health and safety of the presenters, staff and patrons" led to the cancelling of the event at Takapuna's Bruce Mason Theatre.

Auckland Mayor Phil Goff backed that decision, tweeting: "Views that divide rather than unite are repugnant and I have made my views on this very clear."

The Australian-based promoter of the event said he was working with a group in New Zealand looking at the grounds for the cancellation.

"For the mayor to suddenly have a problem with these speakers, is both exceptional, and we're looking at whether it is illegal," Axiomatic Events' David Pellowe said.

Southern's views on immigration have prompted the New Zealand Federation of Islam Associations to ask the Government to bar her entry to New Zealand.

In March, she was barred from entering the United Kingdom, with a Home Office spokesperson saying her presence in the UK was "not conducive to the public good", international media reported.

*This story has been updated to emphasise that the Free Speech Coalition has supporters from across the political spectrum.