Damp English winters are intimately bound up in the popularity and the power of port. Few drinks are better suited to fireside languor than these fortified wines developed in the 18th century for Englishmen, when their beloved bordeaux were interdicted because of warfare and political problems with France. Portugal seemed a good, handy alternative source of vinho, but Portuguese grape varieties and the wines made from them lacked the elegance and strength the English had come to expect. Wines from Oporto were initially mixed with brandy so they would last through the sea journey from Portugal to England. After some experimentation the Portuguese and their English partners, the shippers, discovered that if brandy was introduced earlier in the wine- making process, arresting fermentation before it was compete, the resulting wines were sweeter and fruitier and matured with a marvelous and unique complexity.

Many wine drinkers think port simply isn't worth the trouble. It is too substantial for moderate tastes, too sweet and alcoholic for weight- watchers. Styles and label designations are confusing. Guests often drink too much of it too fast, not detecting the punch beneath the velvet assault. The best vintages must be laid down to drink, it seems, only in senility, when the manual dexterity required to crack a bottle of "vintage" properly is long lost.

In fact, a taste for port is easily developed, as is a working knowledge of its possibilities. Lighter styles are pleasant and relatively cheap. Good port is expensive, but not prohibitive, and will inspire even fading taste buds. Vintage ports are the best, but not for the average wine drinker unless he has sufficient capital to buy older ones for current drinking and the foresight and optimism to lay down recent vintages. Vintage port is declared such by the individual producers in particularly good years and kept in barrel for only about two years; its extreme fruitiness and tannins eventually mellow. Good producers include Crofts, Graham, Fonseca, Taylor, Dow and Warre. Recent declared vintages are '80, '77, '75, '66 and '63. The '77 is a big wine that will offer investors wonderful comfort around the turn of the century. It currently costs about $16 a bottle. A bottle of ready-to-drink '63 is about $40.

"Late-bottled" vintage port is not the same thing as vintage; it is a blend that has spent more time in wood and is therefore softer and more approachable. "Tawny" port is also a blend of vintages that have spent years in cask. This wine is even softer and matures more quickly. Tawny port has lost the purple hue of young port and has acquired an amber hue. "Ruby" port is also a blend of vintages, with less exposure to wood and a bright ruby color. Sweeter than tawny, ruby port is ready for drinking when bottled but is capable of some development. Both tawny and ruby will provide a serviceable introduction, as will any of a number of blends marketed by the big producers. One example is Sandeman's Founder's Reserve, a nonvintage port for about $10 that offers some complexity and a lot of pleasure.

Ironically, because of high liquor taxes and less disposable income, port consumption has declined in England but has increased in other countries. California is making its own variations on port, using varietal grapes for which the state is famous. However, one California port producer, Ficklin Vineyards, makes only nonvintage port from grapes traditionally used in Portugal, a very good home-grown version of the real thing that sells for only $8.