Last month I found myself being driven at high speed across Belgium towards an assignation in a brick-lined basement in Düsseldorf, a town where I knew no one, with a man I had never met.

When I finally set eyes on the man, he did look a little messianic with a black beard and thick, black eyebrows that were permanently raised. He immediately delivered an impassioned explanation of his feelings (for Portugal). I even spotted a fold-up bed in one corner of the cellar. Was this where I would be expected to live for the rest of my days?

Perhaps I should have done more security checks before accepting this wine enthusiast's invitation to taste an unrivalled selection of Portuguese wines. But, as it turned out, in the late afternoon I and my blackened palate were free to go, even if not exactly with a spring in my step after a four-hour tasting of 88 relatively tannic, tart wines.

Carlos Quintas is a Portuguese economist married to a German journalist. Hence his Düsseldorf domicile, frequent trips back to Lisbon and passion for (some) Portuguese wines. His historic cellar in the oldest part of Düsseldorf was lined with cases of fine Portuguese reds, many of them far older than are normally found in commercial circulation. He sells loosely via gatherings of friends and acquaintances in this slightly kitschy 14,000-bottle cellar with its sofas, soft lighting and artworks.

He says he was initially inspired to collect fine Portuguese wine by a little book I wrote on the subject in 1999. This was based on an epic journey made by the Portuguese publisher and his son over the Pyrenees when they drove two bottles each of about 200 Portugese wines to our house in the Languedoc and I tasted my way through them systematically over the summer.

Now, eight years on, I was to be given a chance to revisit some wines and see how they had developed, as well as to acquaint myself with many younger vintages of the same wines.

Quintas had grouped them cleverly in flights of whites, assorted reds, and verticals (several different vintages) of some of the more famous wines - especially those from the regions in which he seems to take a particular interest, the neighbouring regions of Dão and Bairrada in the north of the country.

By the end of the tasting, however, the one wine that stood out was neither a Dão nor a Bairrada. It was, perhaps inevitably, the oldest, a bottle of the 1965 vintage of what was for decades Portugal's only famous fine table wine, Barca Velha, an unfortified wine from the Douro valley made by the house of Ferreira from port grapes traditionally grown mainly on the Quinta do Vale Meão. I must say that the 1999 vintage tasted alongside the hauntingly delicate 1965 seemed a very galumphing, ungracious beast. Perhaps it too will need 42 years to show its best?

There were many such instances of enormous differences between older and younger vintages with, in general, the young wines seeming much closer together in style to each other than the older ones, even if from quite different regions. This mirrors a phenomenon even more pronounced globally whereby so many wines have been made sweet, concentrated and rather heavy. Overall, however, the average quality of Portugal's table wines continues to soar and there is much more fruit in wines made today than a decade or two ago. Furthermore, since the country has kept so many of its exciting arsenal of indigenous grape varieties in the ground, sensibly resisting the temptation to replace them all with Cabernet Sauvignon and Chardonnay, Portugal can offer really distinctive flavours and styles that cannot be found anywhere else.