The Carlsberg Tour of Destruction goes on. Not content with closing three breweries, the Carlsberg Marston’s Brewing Company is now wielding the axe at the famous Burton union system of fermentation.

The Union method was devised in the 19th century as a method of cleansing beer of yeast, and it gave the result not only clarity and sparkle, but an aroma famously known as the Burton snatch – a powerful waft of sulphur from the mineral-rich waters of the Trent Valley used in the brewing process.

Carlsberg is in the driving seat at CMBC. It controls 60 per cent of the business with a chief executive drawn from its ranks. It has little or no interest in either ale or Britain’s brewing heritage.

Since the merger between the Danish lager giant and Marston’s in late 2022, it has closed Jennings, Ringwood and Wychwood ale breweries and now plans to abandon the unions. Once again, CMBC lays the blame on the decline in the ale sector of the beer market and the costs of retaining the unions.

The alleged decline depends on who you talk to. Timothy Taylor in Keighley, West Yorkshire, brewer of award-winning Landlord pale ale and producing 70,000 barrels a year, says it’s back to pre-Covid levels. A similar message comes from Robinson’s in Stockport, which produces 80,000 barrels a year with a pub estate of more than 250 outlets. It has had enormous success with its Trooper ale.

In Surrey, Hogs Back, whose TEA – Traditional English Ale – is a major brand in the South-East – also reports sales back to pre-Covid levels. It has just launched a new subsidiary brewery, One Planet, run by solar power.

Arkells in Swindon, a family brewery dating from 1843, is adding three seasonal ales to its core range this year and is brewing a collaborative beer with Donnington brewery in Stow-on-the-Wold, Gloucestershire.

On 25 January pub chain JD Wetherspoon reported sales in the 25 weeks to 21 January were 10.1 per cent higher than for the same period the previous year. Chairman Sir Tim Martin said: “In the last year there’s been a noticeable resurgence in real ale.”

These breweries and pubs, along with many others, are run by people with a commitment to cask beer. Carlsberg, in sharp contrast, has no such commitment and it underscores this by closing three ale breweries and rubbing salt in the wounds by investing £10m in its lager factory in Northampton.

The case for closing the Burton unions is a familiar one: “time, labour and energy”. There was a time, prior to the creation of CMBC, when different priorities governed production at Marston’s. A message on the website – now taken down – declared: “Pedigree is the only beer to come through the Burton union system. It gives Pedigree its one-of-a-kind taste. No Burton unions, no Pedigree. End of”.

End of, indeed. This is an important piece of British brewing heritage that CMBC is pouring down the sluice. The union system was designed in 1838 by a Liverpool brewer, Peter Walker. He turned an old method known as the carriage cask on its head. The method was messy and unhygienic: fermenting beer rose from the bung holes of casks, ran down the sides and was collected in troughs. The beer was returned by jugs to the casks while the yeast was used for future brews.

Peter Walker’s act of genius was to move the troughs above the casks and link them by pipes. With the carriage system, casks were sent to pubs, but Walker developed large oak casks that remained in the brewery in what became known as Union Rooms. Each union cask holds 150 gallons of beer. The term “union” comes from casks, trays and pipes being linked together or “held in union” as the Victorians said.

The pipes are connected to the bung holes of the cask and then rise up to the troughs. The pipes have swan necks at the top in order that fermenting beer and yeast, driven out of the bung holes by the force of fermentation, drip into the troughs. The troughs are held at a slight angle: the beer runs down the incline and returns to the casks via further pipes, while most of the yeast is retained in the troughs.

Not all the yeast is cleared from the beer. Sufficient is left to ensure a powerful secondary fermentation in the casks when they leave the brewery.

The development of the unions coincided with brewers from many parts of the country, including London and Peter Walker from Liverpool, rushing to Burton to open second breweries there. The brewers were desperate to use Trent Valley water to make the new pale ales that were replacing porter and stout in popularity.

And drinkers wanted clear, sparkling beer, free from yeast. Commercial glass blowing meant pewter tankards were replaced by glass containers. Drinkers could now see the beer in their glasses and murky beer was not acceptable. Before other methods of cleansing yeast from beer were invented, the Burton unions played a vital role in producing beers with clarity and fine aromas and flavours, complete with the Burton snatch.

The closure of such major Burton breweries as Allsopp, Bass, Ind Coope and Worthington means only Marston’s now uses the union system. Should the system become just a museum piece or kept in production? The answer should be a resounding yes for maintaining the system: as the Marston’s website once proclaimed, it gives Pedigree its unique character.

CMBC says the system is expensive to run, employing coopers to repair oak casks and a team to oversee production. But the best things in life are worth paying for. Single malt Scotch whisky has to stay in casks for three long years before it can legally be called whisky and released for sale. Is it worth waiting for and paying a premium? Think of Highland Park, Glenmorangie and Laphroaig and you have the answer.

But, argues CMBC, a large amount of water is used to brew in the unions and clean them and we must be careful to conserve water supplies. Agreed – but water can be cleaned and recycled as a number of breweries, including Adnams, Otter and Purity, prove.

The case for dumping the system doesn’t stack up. The Burton unions played a key role in developing the modern brewing industry and making pale ale and IPA not only national treasures but also the envy of the world.

The unions must not die. Here’s a memo to Carlsberg, purveyor of Eurofizz to the masses: don’t dump on our proud ale heritage.