Guinness plc (known today as Diageo), is a manufacturer and distributor of premium alcoholic beverages. The company was Berkshire's first significant foreign investment. Buffett commented that he viewed Guinness plc as a company much in the same was as he viewed Coca-Cola and Gilette. Similar to Coca-Cola and Gilette, Guinness plc earns a substantial portion of its revenues internationally. Another parallel is that both Coca-Cola and Guinness plc have some of the best beverage brands in the world and were highly profitable companies.
At the time, Guinness plc was the most profitable alcoholic beverage company in the world and second only to Coca-Cola as most profitable beverage company in the world. Berkshire purchased common shares in Guinness plc in 1991, when the company's earnings growth rate was slowing from the previous 25% annual rate.
In 1991, if you assumed the company would grow earnings at 10% per year for ten years and then 5% thereafter, using a discount rate of 9%, the present value of the company would be around 21 billion British pounds. In 1991, Buffett bought shares of Guinness when the market cap of the company was around 9.4 billion British pounds. Buffett managed to buy the company at a 56% discount to the estimated value of the company.