Arthur's Day was an annual series of music events worldwide, originally organised by Diageo in 2009 to promote the 250th anniversary of its Guinness brewing company. It was named after the founder of Guinness brewing, Arthur Guinness. Guinness drinkers were asked by the brewing company to raise a glass to the memory of Arthur Guinness at 17:59 (5:59 pm), a reference to 1759, the year the Guinness Brewery was established. An 82c stamp of an Arthur Guinness portrait was also released by An Post to commemorate the anniversary.