FOR more than 100 years its makers have steadfastly refused to give away details of the secret ingredient in Scotland’s other national drink.

And while the recipe will continue to remain a mystery, the makers of Irn-Bru have created a new version of the UK’s third most popular soft drink, the first for 35 years.

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AG Barr is to launch a sugar-free alternative – Irn-Bru Extra – which will be available to consumers from next month.

The Cumbernauld-based firm already has a sugarless variant but said the latest drink would contain “extra flavour”.

It follows the announcement in March that a sugar tax is to be imposed on the soft drinks industry across the UK.

Irn-Bru is among the fizzy drinks which will be subject to the highest tax band because it contains more than 8g of sugar per 100 millilitres.

The company, which confirmed earlier this year it would be focusing more on low or no sugar drinks in the future, said the idea for its latest creation had been on the table for “well over a year”.

Public health leaders welcomed the decision, saying it demonstrated that the company was taking account of growing evidence on the adverse impact of sugar on weight and oral health in children.

Dr Emilia Crighton, director of public health at NHS Greater Glasgow and Clyde said: “We continue to see the effects of poor diets across Greater Glasgow and Clyde and the increasing impact this has on our services in the form of diabetes.

“People are aware of obesity, but we still have work to do in helping them take the right steps to either avoid it or tackle the effects.

“Soft drinks are the largest single source of sugar for children – they account for 29 per cent of the sugar consumption for 10 to 18-year-olds.

“Given this, I welcome the addition of a new sugar-free version of a very popular soft drink. This demonstrates that the company is taking account of the emerging evidence regarding the impact sugar has on weight gain and oral health in children.”

Soft drinks are the largest single source of sugar for children – accounting for almost one-third of consumption.

Irn-Bru is the third top-selling soft drink in the UK overall, with Pepsi and Coca-Cola occupying the top two spots.

Barr’s said the new drink had been created using the company’s distinctive recipe but would offer consumers “extra taste and no sugar”.

It is only the third permanent variant to be added to the range since the drink was launched in 1901.

Adrian Troy, head of marketing for the firm, said: “It’s clear that the market is changing and consumers want more choice.

“We’ve listened to this and have worked incredibly hard to not only develop Irn-Bru Extra, but to make it available to buy this summer.”

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“As a brand, strength and resilience is at the heart of everything we do and Irn-Bru Extra is a total knockout.

“It delivers extra taste and no sugar. We’re confident it will be just the tonic for those that are keen to try something new.”

The move to introduce a sugar levy, introduced in George Osborne’s March budget, was hailed by campaigners as a significant step in the fight against child obesity.

It is squarely aimed at high-sugar drinks, particularly fizzy drinks and fruit juices and milk-based drinks will be excluded and the smallest producers.

There will be two bands – one for total sugar content above 5g per 100 millilitres and a second, higher band for the most sugary drinks with more than 8g per 100 millilitres.

Analysis by the Office for Budgetary Responsibility suggests they will be levied at 18p and 24p per litre.

Examples of Drinks which would currently fall under the higher rate of the sugar tax include full-strength Irn-Bru, Coca-Cola and Pepsi, and Lucozade Energy and Irn-Bru.

Irn-Bru was launched in 1901 under the name Strachan’s Brew.

The name was originally supposed to be Iron Brew but proposed branding laws forced Barr’s in July 1946 to alter the name as the drink is not actually brewed.

The new ‘Irn-Bru’ trademark was first registered on July 18, 1946.

The secret recipe is known by only three people; Robin Barr, his daughter Julie and one other board member and it is said the trio will never travel on the same plane.

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Irn-Bru is also known for its apparently magical restorative powers as a hangover cure and this prompted Billy Connolly to write and release an ode dedicated to Mr and Mrs Barr “for saving my life on so many Sunday mornings” in his 1975 album ‘Cop Yer Whack For This’.