It could have been different. No lives were lost. Free settlers, the Cartwrights eventually made it to the Sutton region in the 1860s, where they've been for more than 150 years - longer than the capital.

Now the family is looking to sell, rezone and develop almost half of their land - they call it the "back paddock" - in a development which would effectively double the size of the Sutton township.

The proposal would see the 183 hectare block divided into 64 residential blocks, ranging from 5000 square metres to 1.5 hectares, with four environmental conservation blocks up the middle. The development is before the Yass council, with public submissions open till June 26.

The family said it didn't know how much it would make from the development.

Brother Peter and Paul Cartwright, and their sister Robyn Holden, were warned away from farming by their father Bill Cartwright.

"You're not going to be a farmer," he once told the middle child, Peter Cartwright, who became a Canberra firefighter. Paul Cartwright became a police officer. Robyn Holden runs a small business.

Both brothers - their sister was unavailable to be interviewed - have an emotional attachment to the land, becoming close to tears when they talk about it. They're neighbours along Sutton Road.

Paul Cartwright said he recently went up to a hill on his property and sat on a log for an hour, looking at the landscape that his father and mother - Fay - had left to the three of them.

"They lived a very meagre life," he said.

This was because the Cartwright estate had essentially fragmented like an old empire. Parents would inherit land then divide it among their children when they died.

Bill Cartwright struggled with what he inherited. He worked it all himself. The back paddock alone is 183 hectares. The land was shrunk by other family members selling off their shares, degraded from generations of farming and, to top it off, devastated by the Hall-Sutton bushfire in 1979.

So Bill Cartwright took to restoring the land to pre-European conditions. Then he and his wife Fay Cartwright sat his children down and said he wanted to see it developed, but done right, with the profits to go to his grandchildren.

"His view was he was holding on to it. You wouldn't call him an environmentalist," Peter Cartwright said.

"We're not doing this for a profit. We're doing this for dad," Paul Cartwright said.

For them, the land is their sanctuary. Paul Cartwright said when he was a police officer, he would exhale once he crossed the border into NSW. But the farming they do on the land is tiny.

"Farming's changed. Years ago, medium-sized properties could make a reasonable profit. That changed dramatically," Mr Cartwright said.

Climate change, less rain, production costs, rates and insurance had all made farming too expensive.

Peter Cartwright has about 20 calves and five cows. He has to hand feed them all.

Out the front of Paul Cartwright's house is a dam with a pier facing the hills and an English willow on the small island in the dam's middle.

When he built that in 1994, he had a full dam for about a decade. But now it's a shallow pool.

None of them are going anywhere - their sister will soon build a home on her section of land.

"I want to be carried out in a box," Peter Cartwright said.

Bill Cartwright, who died in 2016, and Fay Cartwright, who died in 2014, had their ashes scattered on their land.

"We want the Sutton community to be proud of the Cartwright legacy," Paul Cartwright said.