Glenfield Farm is one of the oldest intact farmhouse groups in the country, having a full complement of farmhouse, dairy/bakehouse, stable, and privy on a remnant of 1.173 hectares. The site is at 88 Leacocks Lane, Casula, NSW. The farm homestead and its outbuildings are of exceptional historical significance as one of the few surviving rural farm complexes in New South Wales dating from the original land grant of 1810 and still capable of use for family living and limited farming activities. 

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It is associated in the 19th century with Dr Charles Throsby, an eminent colonial officer and explorer of his time (1802-1828) and in the 20th century with James Leacock, an innovative dairy farmer, entrepreneur and idealist. 

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Originally a 600 acre grant to Dr Charles Throsby in 1809. Part of 1500 acres granted to Throsby in the Minto area. Macquarie passed through the farm on his 1810 tour of inspection, implying that farm buildings were likely to have been built around that time. 

In 1859 the farm of 1000 acres was leased as a working dairy farm with a mile of river frontage to the George's River, including large areas of rye, field peas, corn and sugarcane as well as 200 fruit trees and vegetable gradens. An underground dairy produced quality butter. Outbuildings included piggeries, cow yards, two large farm sheds, four new farm huts and a substantial brick four stall stable and coach house with a granary above. 

Early 20th century, it was subdivided and sold by Archer Broughton Throsby, although he was recorded as still residing at Glenfield Farm on his death in 1925. In 1920 James Freeland Leacock, who had married a descendent of the Broughton family of Appin, bought Glenfield for a dairy farm.