There should be a Campaign for Real Lager to save a great style from being ruined by beers that are not lagers at all. The word means storage and true lagers are aged or stored for several months.

But most of the leading lager brands on sale today are made in just a week or two and have nothing in common with the genuine article.

I was pleased to find in Marks & Spencer Paulaner Hell, a beer from Munich that’s full of taste and has a fascinating history.

The Germans call Munich München, originally Mönchen, meaning the Monks’ Place.

Centuries ago, a number of monasteries were built in and around the town and most had small breweries attached in order that the monks could have a refreshing beer, especially during the Lent period.

The Paulaner monastery dates from 1634 and the monks found that if they stored their beer deep in ice-cold cellars beneath the monastery it would be kept free from infection during the long, hot summers.

They noticed that at low temperatures fermentation was slow and it took several months for the beer to be ready for drinking. Not science but nature developed lagering.

In common with all the monasteries, Paulaner was secularised in the 19th century and is now a commercial company.

It produces several beers, including a magnificent strong Bock beer called Salvator (7.5 per cent), which means saviour and recalls the brewery’s monastic origins.

The 4.9 per cent Hell on sales in M&S is typical of the everyday beers consumed by Bavarians: Hell or Helles means pale and is used to distinguish the style from dark lagers known as Dunkel.

The label carries an image of St Francis of Paula in Calabria: the monks who built the monastery are members of the Pauline order and should not be confused with St Francis of Assisi, the better known patron saint of animals.

The Hell beer is brewed with pale malt and is hopped with varieties from the Hallertau region north of Munich, the world’s biggest hop-growing area.

With true lager beers, not only is fermentation slow but so also is the first stage of the brewing process known as mashing.

This is when malted grain is mixed with pure hot water and natural enzymes in the grain convert starch to sugar.

Mashing takes place at several different temperatures until the brewers are satisfied the conversion to sugar is complete.

The finished beer has a rich toasted malt aroma and palate, balanced by floral hops and a delicious hint of lemon fruit. The beer is lagered for around 10 weeks.

This painstaking attitude to brewing lager is in sharp distinction to the methods of the giant global brewers.

In 2017 Carlsberg celebrated 170 years of brewing in Copenhagen with a series of events for invited brewers and beer writers from around the world.

At one presentation, a Carlsberg brewer said: "We have taken the lagering out of brewing."

When he was asked to explain, he said modern yeasts and technology meant his beer could be made in a few weeks, not months.

I asked him what he would tell the Czech brewer Budweiser Budvar that lagers its beer for 90 days. "They’re wasting their time!" the man from Carlsberg declared.

A few weeks later I met the managing director of Budvar, Pieter Dvorak, and told him Carlsberg said he was wasting his time using a long lagering process.

He shrugged and replied with a single word that I can’t repeat in English but refers to a delicate part of the malt anatomy.