Mackeson

Mackeson Stout is a milk stout first brewed in 1907. It contains lactose, a sugar derived from milk. Milk stout is a stout containing lactose, a sugar derived from milk. Lactose cannot be fermented by brewers' yeast (Saccharomyces cerevisiae), and the residue adds sweetness, body and calories to the finished beer. Mackeson still bears on its label the milk churn that has been its trademark since it was first brewed in 1907. Milk stout was believed to be nutritious, and was recommended to nursing mothers. In 1875, John Henry Johnson first sought a patent for a milk beer, based on whey, lactose and hops.

Source: Wikipedia