I didn't appreciate how risky - or quasi-religious - the world of top-end wine making was until I started watching a new BBC4 series, innovatively entitled Wine.

Having discovered in the first of the three-part series how posh London wine merchant Berry Bros & Rudd was faring now many of its City customers no longer had jobs let alone dosh to buy fine wines, this week we were given a fascinating insight into the rarefied world of one of the most prestigious wine estates in the world, Château Margaux in Bordeaux (9pm, 23 February).

Like Berry Bros, The First Growth Château Margaux is not best suited to the rigours of the current economic environment, good vintages commanding a gob-smacking £1,000 per bottle. The episode was called The Faith and with good reason - you need a lot of it in this line of work because success or failure comes down to one variable: the weather.

Though the 2005 weather and therefore vintage had been "great", the 2007 vintage was dreadful - or "modest", as it was euphemistically described. And as a wet August made way for a sodden September, the 2008 wasn't shaping up too well, either. Not exactly great news when you're also trying to flog the 2007 vintage to brokers for a paltry €200 a bottle (paltry in comparison with 2005's €350 anyway).

Fortunately, nothing could dampen the enthusiasm of owner Corinne Mentzelopoulos or evangelical director Paul Pontallier. When not casting his eyes to the heavens or waxing philosophical about the qualities of a good wine, Paul was assiduously cultivating new customers - jetting off to Beijing to whip up interest in the 2008 vintage before it had even been bottled.

Then it was back to Margaux to decide when to harvest the grapes. In the last 10 days of September, the sun had finally come out. Should they harvest now or hope for more sun but risk more rain? They gambled and waited. And their faith was rewarded.

Paul reckoned that although the 2008 wasn't likely to be a great vintage, it'd probably be a good one. I couldn't help but feel relieved - even if I am unlikely to taste any Château Margeaux, good or bad, in this lifetime.

Topics