EVERY three weeks, Robin Barr enters the mixing room at his company's Cumbernauld headquarters to create by hand the essence of Irn-Bru from a secret recipe.
But the end of an era is drawing near at AG Barr, a company steeped in tradition.
Mr Barr, 71, is to retire from his role as chairman of the iconic fizzy drinks maker after more than 50 years at the family business, and he will be replaced by a non-family member.
But the fourth generation family member to sit on the board is staying with the company as a non-executive director and will remain the guardian of the secret Irn-Bru recipe.
Mr Barr told The Scotsman: "I'm not ready to pass that on just yet. I'll keep coming in every three weeks or so to mix the ingredients, which form the Irn-Bru essence. I put it together in an 8,000-litre vat and it is then shipped to all of the factories to make up the drink. No-one else is allowed to do it – I've never been able to take holidays of longer than a fortnight."
When he eventually leaves the company for good, he will hand the recipe to his daughter, Julie, who was appointed to the board as company secretary last year.
Ronnie Hanna, the chairman of the oil firm BowLeven, is to take over the role of chairman when Mr Barr leaves in May, following five years on AG Barr's board as a non-executive director. Apart from the company's first chairman – John Allen, who was married to one of the Barr daughters – he is the only person not directly descended from the family to take on the role.
The job of chief executive was given to a non-family member for the first time in 2004, when Roger White was appointed.
In a further boardroom shake-up announced yesterday, Jonathan Warburton, the chairman of the family-owned bread maker and star of the latest Warburton's adverts, is to become a non-executive director.
Mr Barr started his career as a "relief syrup room girl" – taking on overtime shifts to mix the syrup for Irn-Bru in his school summer holidays in 1954. The chartered accountant, who joined the firm as a full-time employee after finishing his financial training, said: "You could say it's the end of an era, but they're still not quite getting rid of me yet, although obviously the day will come when I will step back entirely.
"I have watched the company go through a lot of changes over the years. The main difference has been the scale of the distribution. In 1954, supermarkets didn't exist – we sold to independent shops, most of them in Scotland."
He added: "With a family business, you never entirely let go. You are always interested in it because it remains part of your life and your family's lives."
The new chairman will lead AG Barr through a period of change. The company has diversified into a wider range of products, buying up energy drinks, juices and smoothie brands to keep pace with the changing market.
The firm, which recently made it on to the FTSE 250 index, is weathering the economic downturn and is expected to report profits of about 22.7 million this year – up from 20.8 million last year.
Mr Hanna said: "I would like to pay tribute to Robin, who has overseen the substantial development of the business during his 31 years as chairman. I know I will be heading a strong and stable team with significant opportunities to continue to develop the business."
Long history of Scotland's other national drink
THE basis of the modern company known as AG Barr was established through a joint venture between two family firms in 1901.
The partnership, between the drinks arm of a company run by Robert Barr – Robin Barr's great-grandfather – and the soft drinks business belonging to his son, Robert Fulton Barr, was formed to produce the drink which was originally called "Iron Brew".
Robin Barr's father, Robert, became chairman of the company in 1947.
He was responsible for changing the name of the product – often called "Scotland's other national drink" – to Irn-Bru, after a change in law meant that a drink which did not go through the brewing process could not be called a "brew" .
AG Barr, named after Robert F Barr's brother, Andrew, took over the original Robert Barr business in Falkirk in 1959. Robin Barr became chairman of the firm in 1978, while his daughter Julie was appointed to the board last January.
It has often been claimed that the Irn-Bru advertising tagline "Made in Scotland from girders" holds an ounce of truth – due to the product's 0.002 per cent of iron compound ammonium ferric citrate listed among the ingredients.
Irn-Bru is also well-known in recent years for its memorable and often controversial adverts.