Words failed Liz Sagues when she tried an 80-year-old bottle of this long-lived wine.

This, said Carlos Alves as he poured a deep walnut-coloured wine, viscous and aromatic, is history: “The history of our company, of our country.”

It couldn’t directly be his own history, as Alves – head winemaker at Kopke, established in 1638 and the oldest of many venerable port houses – is far too young to have had any hand in making that 80-year-old vintage tawny port. But he is a native of Portugal’s Douro valley and his family had long made wines for their own consumption.

At Kopke, with its fellow historic names Burmester and Barros, his handiwork has a world-wide market. It’s a big responsibility, if one very much tempered by the centuries of experience.

Alves has no intention of making big changes during his tenure, only implementing the practice of planting individual grape varieties together rather than in the old mixed blocks and employing minor tweaks-for-the-better in vinification that modern wine-making technology allows. “The character and tradition of port wine are unique in the world,” he emphasises.

Port is extraordinarily long lived, and Kopke’s cellars contain bottles dating back to 1890 – sold only in tiny allocations to long-standing clients. They’re wonderful, says Alves, and he has a similar enthusiasm for the four somewhat younger bottles he opened at a trade event in London recently. They dated from the mid-1930s. One was an intriguing 1935 dry white (if a deep golden wine, albeit made from white grapes, can be called white) and the others were colheitas, single-vintage examples of tawny port.

Tawnies, which are mostly blends of averaged years, ie 10-year-old or 20-year-old, mature in wooden casks, where contact with the air changes their colour from the purples and deep reds of bottle-aged vintage and LBV ports.

These wonderful colheitas are sweet, but not in any sickly, cloying way. They have a remarkable level of freshness still and their decades in calm cellars at the port export port, Vila Nova de Gaia, has seen uncomplicated alcoholic fruitiness change to elegant scents and flavours too complex to easily describe.

I don’t suppose it would work to release them in 20cl bottles – all you need is a thimbleful for deep enjoyment – but maybe more half bottles could double the pleasure. Still, you’ve a month to finish off a bottle, unlike the brief once-opened life of a vintage or LBV.

My note for the Kopke Colheita 1935 was simple: “words fail me”. They didn’t – quite – on some slightly more recent vintages: “superb” summed up the 1941, “yum” the 1965 and “spirity but balanced with lovely orange peel-plus flavours” was my verdict on the 1978.

Remarkably, you can buy these extraordinary wines easily on line, at vintagewineandport.co.uk, where available colheitas go back to 1940 (no 1941, unfortunately). The 1965 is £169, 1978 £90, still-a-baby 1984 £55, and one to tuck away for your grandchildren, the sophisticated 2004, £34.50 (standard delivery free on a £100-plus spend).

A Kopke vineyard, Quinta de San Luiz, provided a memorable visit on my first trip to the spectacularly scenic Douro valley.

But my love for the wines has little to do with nostalgia – on a damp, chilly day in London their appeal is just as strong.