The three-roomed pise, or rammed earth, building, known as Lambrigg Cottage, dates back to the late 1880s and is where Farrer developed the first rust resistant strains of wheat which transformed Australian agriculture.

In 1889, the year in which Farrer began his first attempts at cross-breeding to find a hardier wheat strain, wheat leaf rust fungus had devastated the Australian crop.

Losses were estimated at around 2.5 million pounds and the colonies had to import grain to meet domestic demand.

Peter Gullett, whose family has owned Lambrigg since 1949, said the importance of the pioneering agricultural scientist's work could not be overstated. "We take his heritage very seriously," he said. "Having something like this brings responsibility and, on occasion, expense."

While the cottage underwent some renovations in the late 1990s, its condition had deteriorated markedly by 2012. That was when Mr Gullett and his wife Kate decided it was time to set it up for the next 125 years.

"We had never asked for help [maintaining Farrer's legacy] before but, because of the scale of the undertaking, we knew this was going to be expensive."

Mrs Gullett said the assistance from the ACT Government had gone beyond money.

"We were able to access people who could advise on what needed to be done and how," she said.

The result is the complete reinstatement of the exterior, more than half of which had to be repatched with fresh lime mortar, and a tasteful part restoration and part renovation that reclaimed the original layout by opening bricked up doorways and eliminating a wall that had cut the laboratory space in two.

While modern kitchen and bathroom facilities have been added, the emphasis is on originality with Victorian-era windows and glazed doors returned to as new condition.

Some floors and structural timbers, which had proved to tasty for the local termite population to resist, were also replaced.

"We were fortunate to secure the skills of Peter Erland, a local, to handle the lime render," Mr Gullett said. "He had learnt the old skills [of working with pise] off his father. "Our builder, Johnny Gregory of Tharwa, was also a tower of strength. He paid fantastic attention to detail."

Farrer, whose work has helped feed billions of people, was recognised for his achievements by having his picture on the original two dollar note. Born in England in 1845, he studied medicine before emigrating to Australia after catching tuberculosis when he was 25.

He worked as a tutor at George Campbell's Duntroon Station in the 1860s before qualifying as a surveyor.

"At Lambrigg he devised and improvised, culling suitable introductions, cross-pollinating one to another using hairpins until forceps were available and producing hundreds of cross bred plants to be further culled and selected," Farrer's biographer, Colin Wrigley, wrote.

William Farrer never left Lambrigg. He and his wife, Nina, were buried on a hill overlooking the homestead and the flats where his experiments took place on their deaths in 1906 and 1929 respectively.

Tharwa's Gulletts have significant history of their own. Henry "Jo" Gullett, who brought the property in 1949, was the son of Sir Henry Somer Gullett, the World War I correspondent, soldier, and subsequently historian who entered politics and served three separate governments as a cabinet minister.

Sir Henry died on August 13, 1940 in the Canberra air crash credited with bringing down Sir Robert Menzies' first government.

"Jo" Gullett was one of just a handful of Australian soldiers to take part in the D-Day landings. He had been awarded the Military Cross for his actions in New Guinea in 1943.