On the evening of 12 August, Portugal will witness a spectacle last seen from the mainland on 17 April 1912. A total solar eclipse will brush the country's far north-eastern corner, its narrow path of totality crossing the Montesinho Natural Park near Bragança at approximately 7.30pm. The rest of the country will watch a deep partial eclipse hang low over the western horizon, and on the very same night the Perseid meteor shower streaking overhead. Mainland Portugal will not experience this again until 2144. Some wonders, it seems, arrive on a timetable measured not in years but in generations.

It is fitting, then, that this August also sees the release of Taylor's VVOP White — a Very, Very, Old white Port and one of the rarest wines the historic Port house, has ever sold. To carry the VVOP designation, the Port must be over eighty years of age. This extraordinary blend has been drawn from exceptional lots matured in seasoned oak casks in Taylor's cellars in Vila Nova de Gaia, with some component wines dating back to 1896.

Pause on that date. When the oldest wines in this blend were made, the last total eclipse to darken Portugal was still sixteen years from appearing. Crowds who gathered in 1912 beneath smoked-glass viewers to watch the Sun disappear over the Alentejo were, in a sense, contemporaries of this Port. In the Douro of that era there was no electricity; grapes were trodden by foot in granite lagares, and the finished wines travelled downriver to Gaia aboard the traditional barcos rabelos or by steam train. Each glass of VVOP White is a living time capsule from that vanished world.

It is also, quite literally, irreplaceable. Taylor's holds one of the most extensive reserves of very old cask-aged Ports of any producer, and this blend was drawn from a small treasury of old white Port barrels made before the river was dammed. Many vineyards that produced incredible Ports were lost to the hydroelectric programme that began in the 1960s and now lie permanently submerged beneath the Douro river. Once these reserves are gone, they cannot be remade — a genuine scarcity, in the truest sense.

Stewardship of such wines is a generational trust. From Dick and Frank Yeatman (family members) in the early 1900s to Head Winemaker David Guimaraens today, Taylor's blenders have preserved and expanded this diversity for those who follow. The result is a wine of quiet grandeur: luminous golden orange with an amber core, offering dried apricots, almond biscotti, orange zest and wild lavender on the nose, then roasted hazelnuts, tonka bean, blood grapefruit, honeycomb and saffron spice on the palate, finishing with a delicate, lingering salinity.

So, on 12 August, whether you are among the fortunate few in Bragança or watching the partial eclipse from the comfort of your own garden, mark the moment properly. As the light returns and the Perseids begin their night show, pour a glass of a lightly chilled Port. Portugal will next see totality in 118 years; you don’t have to wait that long for your next glass of Taylor’s.

Taylor's VVOP White Port is available from purveyors of fine wines. For further information visit www.taylor.pt or www.HeritageWines.pt (Portugal only)