Owners of vacant land and uninsured properties in the red zone are disappointed but not surprised the Government will appeal against a landmark High Court decision in their favour.

The group of more than 40 property owners calling itself Quake Outcasts and Brooklands property developer John Fowler won their case against Earthquake Recovery Minister Gerry Brownlee in a court decision released on Monday.

In a High Court action last month, they challenged the Crown's offer of 50 per cent of the value of their land, seeking the same compensation offer that other red zone property owners received - the 2007 rateable valuation of their properties.

Justice Graham Panckhurst found the Crown's offer announced by Mr Brownlee last September was unlawful and set aside the offers made to the applicants by Canterbury Earthquake Recovery Authority chief executive Roger Sutton.

And he directed Mr Brownlee and Mr Sutton to "reach a new decision" to buy the properties "in accordance with law" under the purposes and principles of the Canterbury Earthquake Recovery Act 2011.

But Mr Brownlee confirmed yesterday the Government would appeal.

"There are a number of things in that decision that are quite concerning and I think we need to get some clarification around that," Mr Brownlee said.

Mr Brownlee said Justice Panckhurst had invited the Government to speak with him "to seek those clarifications".

"Nonetheless we will try and get our position clearer through the appeal process."

Quake Outcasts spokesman David Millar said the group wasn't surprised by an appeal.

We were under the impression right from the start of the case that if they lost they would appeal," he said.

"They're quite aggressive and very stubborn. They don't want to give in."

Mr Millar said personally he was disappointed at the Government's decision as he expected other group members would be.

"We were quite elated at the result on Monday. We were very pleased and relieved at the decision."

Mr Millar said Prime Minister John Key's comments on TV3's Firstline programme yesterday morning that the Government 50 per cent offer was generous "sounded almost like he's operating some sort of business deal".

Mr Key said the Government would have to "have a good look at the judgement" and decide what it did next.

"But there are a lot of precedent risks here and issues, because if we pay out more than that ... even paying out 50 per cent sets a precedent."

Labour's earthquake recovery spokeswoman Ruth Dyson said red zone property owners had been vindicated by the court decision.

- By Cullen Smith of The Star and Kurt Bayer of APNZ