Annabel Smith draws a pint of deep bronze liquid to her lips and takes a mouthful. A smile crosses her face. “People are always telling me I’ve got the best job in the world — and I have,” she says. “But it doesn’t always feel like that when it’s 9 o’clock on a Monday morning and you have to be drinking beer.”

It is Monday morning but not 9 o’clock. Annabel and I are perched at a shiny wooden bar, the only customers in the room. I look at my watch: it is 11.20. Frankly, that’s still a little early for a pint of Black Sheep bitter. I take a gulp. The beer sluices down my throat but, although it is a full hour and a half before lunch, I can report that it feels good.

I am doing this purely out of duty. As is Annabel, Britain’s first and only female beer inspector. She works for Cask Marque, an organisation of which you have probably vaguely heard without quite knowing what it is. She is part of a mission to make real ale — which until a few years ago was likely to be cloudy, too cold and sometimes worse — the very best it can be.

Cask Marque was set up 11 years ago by four breweries, Adnams, Greene King, Marston’s and Moorlands, which were concerned that, no matter how much effort they put into producing quality ales, once the beer left the brewery it was at the mercy of a pub landlord who could be more interested in his fruit machines. At the time it was estimated that 40 per cent of cask beer served was substandard.

So they put together a team of inspectors charged with making sure that the beer was served properly. In the first year, three inspectors checked out 250 pubs. This year, 49 inspectors, financed by a consortium of 34 brewers, will arrive unannounced at each of the 5,400 Cask Marque accredited pubs. The idea is simple: the oval plaque on the door is a symbol that the landlord cares about his beer.

Annabel, 40, was born to be a beer inspector. She started work in a pub at the age of 20 and four weeks later became the licensee. She remained a publican for seven years before joining Diageo, where, among other things, she taught bar staff how to serve the perfect pint of Guinness. It was an obvious jump to Cask Marque.

So let’s be clear: Annabel and I are not here to enjoy ourselves. “I assume, like wine tasters, we spit it out?” I inquire tentatively. “Certainly not,” says Annabel. “You need to swallow it because the sides and back of your tongue are the only places that detect bitterness.” She does, however, allow herself only one small sip of each pint — crucial, given that she drives 40,000 miles a year between pubs.

Annabel, who has her taste buds tested once a year, gauges each pint according to four criteria: appearance, aroma, taste and temperature. But before she awards my pint any marks, she tells me how it seems: “You’re getting a slightly zesty, citrussy smell coming through. That’s from the hops. Also a malty toffeeness. That’s good. What we’re trying to avoid is anything that smells vinegary or of butterscotch, which is a sign that the lines are not being cleaned properly.”

Worst of all is “a smell like sweetcorn or ketchup — that means the beer has a bacterial infection, which is nothing to do with the landlord, it has come from the brewery and needs sending back”. (Even infected beer can’t do you any harm; “you just won’t order a second pint”.) So, how do our pints of Black Sheep rate? Perfect fives for appearance, aroma and taste but only three for temperature. She sticks a thermometer into her drink: 14.5C (58F). That’s a tad too warm. The perfect pint should be between 10C and 14C, so our beer gets 18 out of 20 — more than the 16 points needed for the pub to retain its plaque.

In fact, this is no ordinary pub. It is the visitor centre at the place where my pint was brewed. Annabel has brought me to the Black Sheep Brewery so I can meet its founder and boss, Paul Theakston.

Although he is part of the famous brewing clan, Paul now has nothing to do with the brewery that bears the family name, which is just yards away from his own brewery in Masham, North Yorkshire. He fell out with the clan shortly after their brewery fell under the control of Britain’s biggest brewer, Scottish & Newcastle, in 1987 (it has since returned to family hands).

Paul is not going to dispel any stereotypes of the real ale enthusiast. He has a straggly beard, tatty shoes and an aversion to market research. “Who drinks Black Sheep?” I ask. “The perceived wisdom would be that it’s someone over 35,” he says. “Beyond that I don’t really know.” His brewery’s promotional video is equally unpretentious, being just that — a VHS video — and featuring morris dancers.

Annabel and I head off to our next beer tasting, at the nearby White Bear pub, and our next member of the Theakston family. Simon, one of four brothers who bought back the brewery in 2003, is Paul’s second cousin. His suit is expensive and his voice as smooth as the beer his company has made since 1827. “The most important thing is the moment the consumer takes his first sip,” he says.

My Theakston’s Best achieves a 100 per cent pass from Annabel. In fact, three quarters of the pints she tests get full marks — naturally, pubs applying to the Cask Marque scheme are usually those that take great care of their beer.

Annabel, outnumbered 48 to 1 by male inspectors, concedes that brewers have not done a great job of getting women to drink real ale. “According to research, 84 per cent of women haven’t tried it,” she says. She blames much of this on the macho marketing of ale, and claims that beer needs to be feminised. “Women say ‘I’ll never order beer on a first date’ so we are campaigning for licensees to get some stemmed glasses behind the bar,” she says, pointing out that many men took to cider only when one company changed the way it was served, in a pint pot filled with ice.

“The other thing is that women are more sensitive to bitter flavours,” says Annabel, “so if a woman’s first experience of real ale is a very bitter pint, she may never go back to it.” Better to start with something more floral, such as Caledonian Deuchars IPA or Theakston’s Old Peculier.

“Don’t say you don’t like real ale, though,” says Annabel. “There are so many flavours, you’ll find one you like.”

Annabel Smith’s favourite pints

Ossett Excelsior Fast-growing microbrewery, a superb 5.2% strong pale ale, both citrussy and floral. A perfect beer.

Black Sheep Riggwelter 5.9% — smells like roasted coffee but tastes of bananas and liquorice.

Fuller’s ESB 5.9% — biscuits, with hints of grapefruit, oranges and lemons. Served in a fantastic stemmed glass as well.

St Austell Tribute 4.2% — a perfect balance of fruitiness and sweet, juicy malt. Great with light foods such as chicken and fish.

Marston’s Old Empire 5.9% — a genuine strong IPA meant for savouring, like a fine wine.

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