The Kentdale Hop Estate, one of the biggest properties in Tasmania, was located fifty kilometers from Hobart and harvested thirty hectares of hops. In 1927 a business disagreement took place between Grant Hay and Carlton & United Breweries over the price and quantity of hops, causing Carlton to cancel its contract with Kentdale. Grant off-loaded his hops successfully to Carlton's interstate rival, Tooheys. He then summoned a meeting of his hop estate managers from Bright in Victoria and the Derwent Valley in Tasmania for a meeting at Coulson Hay & Co. headquarters in Melbourne to establish his own brewery.
On April 4, 1927 Grant Hay wired a cable to Dr Leopold Nathan in Zurich, Switzerland for the order of the first Swiss Nathan Brewing System to be shipped to Melbourne and to be accompanied by Master Swiss Brewer, Heinrich Walter Haenggi of Zurich. Grant Hay proceeded to buy up five industrial sites adjoining his Church Street property. He then ordered a consignment of three thousand units of Purified gin to be shipped from British Army headquarters in Lahore and resold the rebottled gin to American bootleggers in prohibition controlled Chicago, netting Coulson Hay & Co. a million pounds. The brewery was cleared for construction on August 13, 1927.
During World War II, Grant Hay negotiated the supply of Richmond Beer to Australian troops in North Africa and American troops stationed at Sandown Racecourse,
which he owned. He also purchased land on Flinders Island in Tasmania where he stood Fourth Hand, winner of the 1927 Irish 2,000 Guineas and bred champion Australian racehorse Counsel, winner of the 1944 Caulfield Cup and champion American racehorse, Warra Nymph at Del Mar. Grant Hay also owned the seventy-two foot ketch, "Jane Moorhead" which was used by General Douglas MacArthur for the Allied troop landings in the Pacific.