An Edinburgh brewery has launched a new nitro stout beer following a surge in demand for darker beers amid well-publicised shortages of sector giant Guinness.
Vault City, a craft brewer dubbed the “mad scientists of sour beer”, has created the Nitro Mini M*rs products, which will be launched in the off trade on March 4 – just ahead of St Patrick’s Day on March 17.
The brewery has created its first-ever nitro pastry stout, a dark, smooth, and velvety brew that is slightly higher in ABV than a typical nitro stout or porter, giving a more intense, sweeter flavour profile but still delivering that iconic nitro bubble rise. Vault City have dabbled in pastry based brews before – pastry sour Blueberry Boysenberry Cobbler and vegan imperial pastry stout Kärleksmums – but this is its first nitro pastry stout.
The Nitro Mini M*rs is a fun-size take on Vault City classic Double Deep Fried M*rs, which remains one of the firm’s highest-ever rated recipes, and there has been the also-popular reduced ABV Mini M*rs Stout.
The new nitro version is packed with all the chocolatey, caramel goodness of the original, now with a lower ABV and a smooth, creamy nitro twist while still paying a true homage to the mighty M*rs Bar.
The launch comes on the back of higher demand for Vault City’s range of stouts, which in turn follows shortages of Guinness as the black stuff gains popularity.
Guinness owner Diageo said in its recent 2025 interim results that total net sales in Britain grew by 2%, “mainly driven by strong Guinness performance, despite the temporary supply constraints in the half”. At a global level, the iconic Irish tipple enjoyed double-digit growth for an eighth consecutive half.
There have been reports of Guinness shortages as it grows in popularity among a wider range of consumers, including women and younger drinkers, boosted by social media campaigns. The firm even said it was making more Guinness than ever, and working hard for supply to meet rocketing demand.
A recently published study by beverage alcohol data and intelligence expert IWSR described stout as “defying gravity in a lacklustre UK beer market, enjoying a notable upswing since the Covid-19 pandemic thanks to a combination of attention-grabbing publicity moments and the attraction of a broader demographic”. It said stout volumes in the UK, the segment’s leading global market, grew by a quarter between 2019 and 2023, and by 12% in 2023 alone.
Vault City said its new nitro product, which has an ABV of 6.2%, serves as a good introduction to stout, with its sweet and familiar flavours making it more approachable for first-timers than more bitter existing products. The Scottish Brewery also said it has been looking to launch more dark beers after winning several Untappd awards for best pastry stout (and the highest rated beer in the UK in 2023). Its other products in the category include a Gingerbread Latte Imperial Stout.
The new products are another milestone for rapidly growing Vault City, which launches a new beer flavour every two weeks. It currently makes more than a third of the sour beers consumed in the UK, while it is relocating to a new brewery able to produce more than 10 million litres of beer per year on the back of a £330,000 crowdfunder.
Its products are stocked by Tesco, Asda, Morrisons, Sainsbury’s, and Waitrose, and it exports to more than 250 countries.
Steven Smith-Hay, Vault City’s co-founder, said: “We believe the product we’re launching is a sparkling new gem in the stout category, with a smooth, sweet, and velvety finish appealing to a wide range of consumers, from sector incomers to incumbents.
“As St Patrick’s Day approaches, we’re encouraging beer-drinkers to look beyond the black stuff and sample something new – they might even like it better!”
The Nitro Mini M*rs products retails at £5.60 per 440ml can.
To browse Vault City’s beers, visit www.vaultcity.co.uk/
