Cru is one of those words that you will see emblazoned across a reasonably significant number of French wine labels. But what does it actually mean?

It is one of those French words that has an unhelpful number of meanings - raw' being one and coarse' being another. However, used in wine circles the word is significantly more majestic.

In this environment a cru' is a vineyard or, more accurately, a specific site or plot. The reason it's being pointed out to us, the consumer, is that it normally suggests a wine of quality, the vineyard or site having being identified as one that produces some of the best grapes from within a broader area.

You will come across it on wines from all over France's wine-producing regions, one of the most famous of which is Chablis.

Ah, Chablis. I love everything about Chablis. I adore the town; the local restaurants are fabulous and the countryside is beautiful. Perhaps, though, the thing I like most about Chablis is that it has stood stoically by its beloved chardonnay with a sort of steeliness that resonates in the wines and the people that make them.

I am still amused by the number of people who tell me, so adamantly, that they will never, ever, drink chardonnay. No, what they would much rather drink is a nice glass of Chablis.

It says much for the determination of the wine-makers of Chablis to promote their wines based on provenance and style rather than grape variety. For that, I salute them.

An invitation to a tasting of Chablis' Grands Crus' wines was not one I was going to let go by. You will have noticed that these were not going to be any old cru' wines. These were wines from the Grands Crus' vineyards.

Chablis has seven Grands Crus' sites which are clustered together on a single hillside to the north east of the town. The seven sites are (from west to east) Les Bourgos, Les Preuses, Vaudésir, Les Grenouilles, Valmur, Les Clos and Blanchot.

It is nigh impossible to articulate in words how individual and unique these vineyards are - despite their close proximity on a block that must be less than one mile in length. Some 100 hectares may be planted to vine in the grands crus sites but total production is less than three per cent of all the wines produced in Chablis.

In short, these wines are the haute couture of the wine business - tiny volumes, each wine individual and an expression of its origin and style of the winemaker.

In geological terms, Chablis lies along the southern extremity of the Paris basin, which stretches across northern France and the Channel to southern England. These are sedimentary soils formed from an Upper Jurassic seabed about 180 million years ago. Lime-clay soils are dominant, but the geological originality of Chablis resides in its sub-strata, often quite near the surface, of Kimmeridgean limestone, formed by billions of tiny fossilised shells.

The Grand Cru vineyards are planted on slopes which have limestone outcrops that are quite unique, and it is this, combined with the exposure to the sun, that give the wines the power, finesse and longevity that makes them so special.

I will not beat about the bush with you here. I am not a lover of all of the grand cru styles. Many critics and wine-lovers enthuse wildly about the wines of Vaudésir and Les Clos. Both vineyards share deep soils with a heavy clay element. It is this that gives the wines their weight and richness. It is certainly true that the wines will keep, ten years, at least and maybe in excess of 40 and their qualities are indisputable. Still, wine is notoriously subjective and I was definitely falling for the less famous vineyards.

I was much, much more excited by the floral, aromatic qualities of the wines of Blanchot and, despite the fact that they seem to be destined to be squeezed out by the bigger, more famous names, I was utterly charmed by pretty much every single wine from the Bougros.

The wines were accessible and elegant. A tasting of Joseph Drouhin wines showed a delicious 2006 Bougros with a smoky, skinned-almond quality and a fabulous mid-palate. Moving back to 2002, the Bougros had acquired a floral and honey nose and a vibrant, expressive palate. I thought the 2002 was drinking just perfectly and it scored one of my best marks of the tasting.

William Fèvre was showing two wines from Bougros, both from the 2006 vintage. The first was the straight Cru Bougros and again I was drawn to the vibrancy and the mineral freshness of the wine. More of that famous Chablis minerality was to come though.

The Cru Bougros Côte Bouguerots' is made from grapes that come from vines planted on deeper soils than the first. The bouquet was very intense with strong mineral-like qualities. The wines were so different I could barely believe it. Les Bougros covers no more than 13 hectares and yet in such a small site, two very different wines, from the same grapes, had been produced.

Tracking down these wines isn't such an easy task, but it can be done!

You can buy a case of six of the William Fèvre Crus Bourgos Côte Bouguerots' 2006 at Majestic. The price is £165. The Drouhin wines are available through Bennets Fine Wine Merchants (Chipping Campden, 01386 840392 www.bennettsfinewines.com). Sadly, they don't have any of the 2002 that I loved but, at the time of writing, they had nine bottles left of the 2000 vintage.

You may be interested to know that Bennets have just put together an offer of Drouhin wines from the 2006 vintage. If you are interested in receiving a copy, please contact Richard Brooks, the general manager.