THE VIRTUES of drinking "vintage port" have been extolled over and over by numerous Englishmen whose fondness for this strong, fortified wine has remained unwavering

While drinking vintage port is de rigueur among the English, it has been only recently that the merits of this heady beverage caught the fancy of significant numbers of wine-conscious Americans.

The origins of port can be traced back to the late 17th century to an Englishman named Ernest Cockburn. While Cockburn's sons were traveling through northern Portugal, they became so enthralled with a local red wine that they purchased several barrels of it to be shipped from Oporto to England, adding a bit of brandy to help the wine withstand the rigors of sea travel. From this sprang the port trade and the birth of vintage ports.

Vintage port is produced in the Upper Douro valley in Portugal only in years when the grapes are considered of exceptionally high quality and when the prevailing market conditions indicate that another vintage port will be commercially acceptable. Consequently, there are usually no more than three years in every decade declared by port producers as "vintage years." This practice is intended to foster high-quality vintage ports, since they are only produced in the finest years. Additionally, it creates a certain degree of the scarcity and mystique that helps to sell vintage port.

The port industry is dominated by a handful of firms which to this date maintain very high standards. Some of the finest names in the trade include Taylor, Croft, Fonseca, Graham, Dow, Warre, Quinta Lo Noval, Sandeman, Cockburn, Rebello Valente, Offley Forrester and Smith Woodhouse. These firms maintain commercial operations called "port lodges" in the city of Oporto. Although the style of port produced by each firm varies, any port with these companies' name on it is usually well-made.

Since the turn of the century, vintage port has been aged two years in oak barrels and then bottled. But it has only been in the last two decades that the bottling operation has taken place at the port lodges in Oporto. Previously, most vintage ports were shipped to England for bottling, often making the quality dependent on the expertise and honesty of the English bottling firm.

Vintage port represents the apogee of winemaking in Portugal, and there is no other wine in the world comparable in style, although several California wineries, particularly J.W. Morris and Quady, have come very close to emulating a great vintage port. Fortified with brandy and reaching alcoholic levels of 20 to 22 percent by volume, it is strong and rich. It also throws a heavy sediment after only a few years in the bottle, making decanting mandatory, and needs 15 to 25 years to mature.

Old vintage ports are much in demand and fetch ridiculously high prices. Locally, consumers can often spot good wines from such excellent vintages as 1966, 1963 and 1960. In the '70s, the only years declared by a majority of the port trade as vintages were 1970, 1975 and 1977.

It is the extraordinary quality of the 1977 vintage ports that has enthusiasts buzzing these days. The quality is so exemplary that even nonport drinkers should consider laying away a few bottles. In talking to vintage port fanciers who have had the experience of tasting the 1970s, 1963s and 1955s at a similar age, most were in unanimous agreement that the 1977s are the most successful ports they had ever sampled. The depth of flavor of these 1977 ports is remarkable, and combined with their impeccable balance, this vintage is potentially the best in the post-World War II era. These will require a good 10 to 12 years to mature, and will no doubt last well into the 21st century. However, because of the immense fruit and lush, savory character, the 1977s have an appeal that makes them relatively approachable in their youth, despite their high tannin content.

Vintage port is best drunk at the conclusion of the meal in the fall and winter months, with one of the fine English cheeses which seem to have been made to complement this fortified wine. I would recommend any good stilton, cheshire, gloucester or cheddar, although some port enthusiasts eschew cheese in favor of walnuts.

Locally, most of the better wine shops have a representative selection of the more recent vintage ports, but for the largest selection, and for the hard-to-get older vintages, Elliott Staren of MacArthur Liquors is the man to contact.

Here are my recommendations from the sensational 1977 port vintage. The evaluations are listed in order of overall quality with the highest-quality wines appearing first. You should remember, however, that any of these 1977 ports listed below is pretty exceptional from a quality standpoint.

Taylor Fladgate and Yeatman 1977 ($17.95-19.95). This wine is as close to perfection as a wine can get. Dark purple and opaque, the bouquet virtually explodes with ripe fruit, violets and spicy oak. Extremely rich, slightly sweet and textured on the palate with outstanding balance and heavy tannins, this extraordinary wine should approach maturity in 10 to 12 years, and age well for 40 or more years. A triumph in winemaking. Very limited quantities.

Graham's 1977 ($15.95-18.95). Deep ruby-purple with an enormous black currant, peppery, spicy aroma of full intensity. As rich as the Taylor, but slightly more sweet and lower in acidity and tannin, this wine has hugh extract and viscous, mouth-coating flavors. A big, plump port needing eight to 10 years of bottle age, but will age magnificently for 25 to 30 years.

Warre 1977 ($15.95-17.95). Considerably tougher and more tannic than the Graham's, this big, rough, relatively dry port has rich, briary, peppery fruit, and is extremely full-bodied with significant tannin. Intense extract, but very well-balanced components suggest a long, celebrated lifetime for this wine.

Dow 1977 ($15.95-18.95). Dark ruby-purple with the murky purple denseness characteristic of this vintage. Rich, briary, peppery with a heavy perfume of ripe fruit and oak. Very full-bodied with excellent concentration, extremely tannic for a Dow, this big, slightly sweet port should mature in 10 to 12 years and hold for 20 or more years.

Fonseca 1977 ($15.95-16.95). By itself, I rated this wine considerably higher, but among the company of the best 1977 ports, it suffers a little in comparison with the extraordinary wines from Taylor, Dow, Warre and Graham's. Dark ruby with a spicy, rather forward chocolatey aroma. Rich and spicy on the palate with very good concentration, huge body and moderate tannin. More forward than the previous ports, this Fonseca should mature in 8 to 12 years.

Sandeman 1977 ($19.95). Briary and peppery with a very full bouquet of ripe fruit. Full-bodied with viscous, medium-sweet flavors and a dry, long finish, this is one of the finest Sandeman ports in years. Given 10 to 12 years to develop (as there are astringent tannins at present), this should be a fine, medium-weight port.

Royal Oporto 1977 ($10.95-11.95). The fact that Royal Oporto made such an attractive port in 1977 is indicative of how exceptional this vintage is. Dark ruby with an open knit, forward, fruity, spicy, peppery aroma. Moderately rich and soft on the palate with good fruit, oak and medium tannin present. A pleasant port which undoubtedly suffers in comparison with the bigger, richer, more tannic wines above.