Hertfordshire is a county with a bountiful supply of brewers, 16 in total. Many of them are relatively new, brewing vibrant interpretations of classic beer styles, such as porter and IPA.

And yet, in a blind tasting by a panel of experts at St Albans beer festival, who should come top of the crop as Champion Beer of Herts but McMullen with their AK Mild.

The family company in Hertford was founded in 1827 and it’s been brewing AK almost since its inception.

As one of the judges, I was delighted by its victory – and so was director Fergus McMullen, who says it’s the best thing to have happened during his 40 years with the brewery.

I share his pleasure as I think Mac’s beers tend to be overlooked, AK in particular. I think it’s a superb ale with a wonderful balance of malts and hops and a refreshing palate and finish.

The brewery was founded by Peter McMullen of Scottish and Irish descent. He was a cooper who thought it would be a good business venture to make beer to fill the casks he made.

He started to buy pubs and today the company has an impressive estate of 126 outlets in Herts, Essex and London. They include the old coaching inn, the Peahen, in St Albans, and the recently opened Saint & Sinner on St Peter’s Street.

In the early 19th century mild ale was the most popular style of beer, consumed in large quantities by agricultural and factory workers. It was relatively low in alcohol in order that consumers could down several pints but still be fit for work.

AK is 3.7 per cent and remains one of the brewery’s top brands. It’s brewed with fine water from an artesian well with Halcyon pale malt, a small amount of darker chocolate malt and maltose syrup. The single hop variety is the Whitbread Golding from Kent.

There’s another Whitbread connection, for the house yeast culture originated in the Mackeson Brewery in Hythe, Kent, famous for its milk stout and owned by Whitbread in London.

The yeast gives a rich and fruity character to the beer with floral and spicy hops on the aroma with juicy malt and tart orange fruit. Biscuit malt, tangy fruit and delicate hop resins dominate the palate while the finish is dry with a good malt character balanced by orange fruit and hop resins.

There’s been a long controversy over the name of the beer. Some say AK is the result of misspelling that meant the letters stood for All Korrect or All Klear.

My own theory is more prosaic but more likely. It’s based on a system of branding casks with letters before such modern marketing as pump clips, bar towels and beer mats came into use.

For centuries, a widely used form of branding was the letter X to denote strength: the more Xs, the stronger the beer. In Victorian times, when the two main types of beer were mild and pale ale, the latter continued to be branded as X while the letter was split vertically to make a K for mild.

At a time when McMullen produced more than one mild ale, AK meant it was either the first of the batch or that it was light mild rather than a darker version.

You can enjoy AK in the Peahen. The beer festival organisers invited the manager of the Saint & Sinner to sample the beer in the hope he will add it to the beers on his bar.

If you can’t see it, say: "I want a pint of AK – All Klear?"

In the beer awards, Farr Brew’s Mannered came second and two beers vied for third place: Garden City Brewery in Letchworth with its Pale and Two Bob in Old Welwyn also with a beer called Pale.