ST PATRICK'S DAY on March 17th is an opportunity for Irish people around the world to celebrate their heritage. For Diageo, the world's biggest maker of alcoholic drinks, it is an opportunity to sell them Guinness, a stout brewed in Dublin since the 18th century.

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This year, Diageo hopes to sell 7.5m pints of the black stuff on St Patrick's day alone. Since 2009, it has stepped up its marketing efforts for Ireland's national day, as well as for "Arthur's Day", a pseudo-national celebration it created that year. These efforts appear to be paying off—in January, Diageo announced that sales of Guinness in its homeland had risen last year for the first time since 2008.

But analysts question whether focusing marketing around national holidays is the best way to rebuild the brand. Although sales are no longer declining in Ireland, they have not had much of a boost there much either. The story is grimmer in Britain, where sales are plunging: in 2014 Diageo lost eight times as many sales of Guinness in Britain as it gained in Ireland (see chart). Americans are also downing far fewer pints of Guinness, though the drop is at a slower pace than across the Atlantic.

Drinkers’ changing tastes spell more bad news for Guinness, even if it maintains its market share. The total volume of beer downed in Britain and Ireland has fallen by 20% over the past six years, according to Euromonitor, a research firm. And the story is not any frothier for rivals in their home markets. Americans are downing fewer Budweisers. Carlsberg, a Danish beermaker, and Heineken, a Dutch competitor, are also struggling to revive revenue growth in Western Europe.