End of the dynasty that made Irn-Bru – from girders

For years, its slogan was "Barr's Irn-Bru: made in Scotland from girders". But now the beloved Scottish fizzy drink's catchphrase is wrong in two ways: first, the closest it gets to girders is 0.002 per cent of ammonium ferric citrate listed in its ingredients. And second, the last member of the Barr family, who have made Irn-Bru for more than 130 years, is to step down.

Robin Barr, whose great-grandfather set up the family business in 1875, said he was retiring as chairman of AG Barr in May, after 31 years of running the company. His decision all but ends the Barr family's involvement with the bright orange-coloured drink that has been synonymous with Scottish culture for more than 100 years. Until six years ago, Irn-Bru was one of a couple of brands in the world to outsell the behemoth Coca-Cola on home soil. The other is Inca Kola in Peru.

Under Mr Barr's chairmanship, Irn-Bru was launched in a host of other countries, including Russia (where it is much-loved), Ireland, Poland, Greece and the Middle East. A G Barr has other brands including Tizer, which it bought in 1975, and Strathmore Spring Water, but Irn-Bru which remains its most powerful and recognisable brand.

At the heart of Irn-Bru's success has been its powerful advertising campaigns, which have not only tapped into the Scottish sense of humour but also national pride. In fact its slogans, "made in Scotland from girders", and "Scotland's other drink", referring to whisky, gave it a resonance that extended way beyond Scotland's borders.

Other ads involved a man singing a song about his girlfriend who liked Irn-Bru and was therefore perceived to be more macho than he was. The lines went: "They say that love hurts but that's an understatement, With you love makes me turn black and blue. Got a funny feeling you've been drinking Irn-Bru". It is so revered that when McDonald's opened in Scotland people complained, and apparently picketed, the restaurants for not selling Irn-Bru. It is available in some branches.

The Barr family's ability to maximise the brand's value and capture the zeitgeist has been evident throughout Irn-Bru's history. For instance, Iron Brew was rebranded Irn-Bru in 1947 as fears grew that the Labour government under Clement Attlee was to change food-labelling laws to ensure product names had to be literally accurate.

Mr Barr's great-grandfather Robert founded the business in 1875 in Falkirk. Two years later, his son, Robert Fulton Barr, started a second soft-drinks business in Glasgow, taken over by his brother Andrew Greig Barr in 1892. He started selling Iron Brew in 1901, initially under the Strachan's brew name.

In the UK, Irn-Bru is the third-biggest selling soft drink, after Pepsi and Coca-Cola. Last year, AG Barr said that Irn-Bru's sales were bigger than those of Lilt, Sprite and Tango combined.

Mr Barr, 71, who still owns 6.5 per cent of the company, will stay as a non-executive director. Ronnie Hanna, who has been a non-executive director for five years, will become non-executive chairman. But another family member, Julie Barr, remains A G Barr's company secretary and legal affairs manager.