Despite the positive press it enjoys, and the energetic activity of the enthusiasts who love it, until recently, real ale was making little significant impact on the wider beer drinking public. In sales terms, ales and bitters were in general decline, and with even cask ale often characterised unflatteringly as an old man's drink, its future was far from secure.

This year, however, there has been concrete good news. Recent figures show that, for the first time in 50 years, ale increased its market share, at the expense of lager, with small real ale brewers doing particularly well.

There are various reasons for this, from the increased interest in local, artisanal products, to the fact more supermarkets are selling bottled ales, but, undoubtedly, there has been also been a significant shift in the real ale demographic. Its popularity among women and younger, 25 to 34-year-old drinkers is soaring, with this year's Cask Report suggesting boldly that "the negative stereotype of cask ale and cask ale drinkers has disappeared".

If it has, that is down, in no small part, to a small spearhead of microbrewers who have been determinedly modernising real ale's image, to both capitalise on and further cultivate this reawakening of interest. One outstanding example is Warwickshire's Purity Brewing.

Owner Paul Halsey had always been mystified as to why real ale was marketed almost exclusively to 40- to 60-year-old men, using stock themes of tradition and heritage. Brew good beer, he reasoned, and those drinkers will buy your product, regardless. Instead, when he launched the business in 2005, Halsey dedicated himself to creating a dynamic contemporary brand that would reach out to younger and female drinkers. He wanted, as he puts it, to make cask beer "a little bit cool".

Five years on, Purity has just announced a 53% year-on-year sales increase and plans to soon more than double its output to 400 barrels a week. Halsey has spread the word, primarily, by embedding Purity in the Midlands' arts and music scene. The company sponsors the Moseley folk and jazz festivals; the avant-garde film and music event Supersonic; and the Birmingham Comedy Festival.

At the same time, he developed the brewery's online marketing, attended food as well as beer festivals, and got involved in all sorts of projects that aim to modernise real ale's image, and broaden its fan base. These range from Marverine Cole's Beer Beauty tasting sessions for women to beer and food matching evenings at the Michelin-starred restaurant, Simpsons.

Crucially, he made sure Purity looked good, too. The company designed sharp, modern and easily understood packaging for its beers, and added colour by naming two beers after animals on Halsey's farm, UBU the dog and Mad Goose, with logos and pump clips developed around them. As far as Halsey is concerned, such crisp design was crucial in getting the likes of Hotel du Vin and Malmaison to take the products seriously, and getting trendy pub groups like the Midlands-based Peach chain to list his beers. "Five years ago," he says, "these places wouldn't have taken cask beer seriously, but they do now. Our brand sits nicely with them."

Such activity, and particularly the idea of creating an identifiable brand are anathema to many microbrewers. Indeed, purists may despair at overtures to the "lager boys", such as offering slightly colder than normal Purity Gold alongside Carling in a couple of cricket clubs to lure lager drinkers across. This cooler pint - the same colour as Carling, but a damn sight tastier - has won over plenty of converts. "The fact is younger women and guys love refreshing beer styles," says Halsey. "They don't want warm beer. That's why, historically, in summer, cask ale sales flopped. Light, interesting, hoppy beers - that's the market that's exploded over the last few years."

If the wider real ale community has acknowledged that thirst for lighter, paler golden ales, like Summer Lightning and Exmoor Gold, then brewers - and, in my opinion, CAMRA - have been slow to try and cultivate the next generation of real ale drinkers in a credible and and intelligent way. You may dismiss Adnams Spindrift (brewed like ale, served like lager) as a novelty, but is at least an attempt to do something new. There are still too few brewers like Purity, Otley, Marble Beers or Thornbridge who - in everything from their variety of beer styles to their hip city-centre bars - are attempting to map out real beer's future.

It's been suggested that one group that needs to modernise, and fast, are the mid-sized regional, family breweries - Robinson's and JW Lee's are good Manchester examples - who, broadly speaking, are still brewing boring brown bitters for old men. They can't transform themselves into hip brands overnight, but they need to do something to revitalise their pubs, their beers and the public's perception of such (Joseph Holt, for instance, has a slightly more interesting range than you might think). Otherwise, they will die out with their current audience. Call it natural wastage.

Which brings us to the central question - is Purity a model modern microbrewery? Will traditional brown beer ever die out? And which other small breweries are actively cultivating real ale's next generation?