The Cabramatta home in Sydney's southwest sold on Friday for $1.15 million, well above the price guide of between $720,000 and $750,000.

The house was due for auction on Saturday, but instead two parties battled it out for three hours on Friday afternoon.

The winning group was led by Gough and Margaret Whitlam's son Nick Whitlam and former NSW premier Barrie Unsworth, and includes NSW Labor president Mark Lennon and Unions NSW boss Mark Morey.

The group set up the company Whitlam Heritage Home Limited, solely to buy the house which was owned by the Whitlams from 1956 until 1978. Mr Whitlam was prime minister from 1972 to 1975.

Bidding on the original four-bedroom home started at $905,000.

Mr Unsworth said the hope now is to preserve the house for posterity with an appeal to be set up for the public to contribute funds.

The former Labor premier told AAP he hoped the Commonwealth or NSW government, or the Whitlam Institute, would eventually acquire the house "for the benefit of future generations".

"We want to tell the story to future Australians ... we've got the house for the benefit of the people of Australia," Mr Unsworth said.

Mr Unsworth said there hadn't been a lot of changes made to the house since the Whitlams lived there.

Real estate agent Manuel Roussakis from Ray White Canterbury told AAP the sale price was much higher than the vendor's expectations.

"It was between two groups going backwards and forwards for quite some time ... about three hours, battling it out for a slice of Australian history," Mr Roussakis said.

He said the modest brick home still had the original layout and some of its original features.

The home was last sold in 1990 for $154,000.

Australian Associated Press