110 S. Pitt St., Alexandria. 836-2749.

Open Monday through Saturday, 11:45 a.m. to 2:30 p.m. and 6 to 10:30 p.m. AE, BA, MC. Reservations.

Prices: Main dishes $5.80 to $12.

A certain courage is required to design a restaurant without a front door. The Wayfarers has a painted sign swaying over its facade and windows that allow the soft glow inside to beckon the passerby. But the door is hidden down the alley, and those who stride purposefully to it are immediately identified as old timers.

They are also identified as people who know how to find a good restaurant, for the Wayfarers is a British-style Colonial tavern that could make most French restaurants step up their vigilance.

Its menu consists mostly of English meat pies and veal dishes. Also offered are roast beef and lamb chops, beef Wellington, and a chicken concoction, plus several seafood specials each day. There are also some very compelling appetizers.

Avocado Elizabeth may sound too closely related to that deservedly maligned dish. Waldorf salad, but it is an inspiration. Matchstick pieces of apple are tossed with shrimp, nuts, celery and a pale green avocado dressing, and mounded in an avocado shell. The mixture is light and delicate, a most refreshing start. Oyster stew at the Wayfarers is a grand dish, the oysters lightly poached in an onion-scented cream and topped with crisp bacon strips. It is not a soup but a sauced dish of oysters, and its preparation is faultless. Beyond those two inordinately good appetizers, the diner encounters wonderfully unctuous eggplant and mushrooms in a tarragon marinade and a seafood pie that suffers somewhat from toughness of its crustaceans, though its crust is commendable. The menu also lists a few soups, all of them creditable. One wonders, in light of these, why the Wayfarers serves a salmon pate that tastes like molded canned tuna.

Salad at the Wayfarers would be an appropriate substitute for an appetizer, as it is a kind of mixed hors d'oeuvre of marinated vegetables - potatoes, white beans, beets, green beans - on Boston lettuce with a ripe tomato garnish.

But good as the appetizers and salad are, this is a restaurant where the main dishes are the stars. If you have only one dish to taste, let it be veal. Try, perhaps, the Wayfarers Special, a thick veal chop buried in diced ham, mushrooms and chopped walnuts, all blended into an exceedingly rich cream sauce. Or turn to the veal Windsor, the quarter-inch-thick veal scallops sauteed no more than necessary, ladled with a pale pink cream, tomato flavored but not at all acid, garnished with an artichoke puree in a mushroom cap. Veal at the Wayfarers is well-chosen, well-butchered, well-cooked, well-sauced. I only wich I had had the time to try it with almond cream, lemon cream or with sweetbreads, mushrooms and cream.

Breaking away reluctantly from veal in cream, one must - if only for the sake of tradition - consider meat pies: steak with kidneys, mushrooms or oysters, or veal with ham, mushrooms and sweetbreads. The puff pastries are flaky, the gravies rich, and if the pies don't approach the subtlety of the veal dishes, they are what they are meant to be: hearty English food. Fish at the Wayfarers - fresh and juicy, delicately sauced - also deserves notice. And at an English-style restaurant one attends to the roasts and grills, in this case being thick lamb chops slathered with mustard and garlicky crumbs. Cooked pink, with their surfaces well-browned, the chops are the glory of the Empire. Roast beef, on the other hand, is tender, flavorful meat but ours was cooked beyond the rareness we requested, and tasted unnecessarily dry. It was out-classed by its pungent horseradish bread sauce and crisp Yorkshire pudding.

Several nice things happen along with a meal at the Wayfarers. The bread is dense and homemade, one day whole wheat, another day white; one day a little undercooked, another day just right. Crusty oven-browned potatoes appear on the plate, and a bowl of fresh vegetables - carrots, maybe, or slightly undercooked herbed green beans - is brought to the table.

Dessert begins to seem superfluous. But the rum baba is worth a try. The trifle could stand a trifle more enriching, the tart some lightening of its texture. Small matters against the grandeur of the first two courses.

A larger matter is the service. Sweet young serving wenches are, I realize, in the British tradition. But they ought to be trained past halting timidity. They ought to be able to recommend a wine more sophisticated than Blue Nun. They ought to make sure all your silverware and side dishes have been brought, and to ask whether you want dessert, before they bring the check. And in rooms so carefully decorated as the Wayfarers', they ought to dress with a little flair; be it in jeans and T-shirt or more formal dress, at least the halves should be complimentary and the whole seem more than a thrown together covering for running down to the laundromat.

For the rooms are painstakingly attractive. In front, two small rooms with about three tables each are papered in parchment-toned florals, their woodwork painted Colonial green. Built-in shelves display Blue Willow china. The dark floors are left bare except for heavy wood tables and carved highback chairs. Tables are set with handwoven wool mats and tall white candles in hurricane lamps. The totality is graceful, except for the straggly dried flowers in tiny dirty vases and the echoing clatter in a room with neither rugs nor drapery. The rear rooms are dominated by a well-aged bar, set with rough wood and tile tables against the original brick walls. The floor is brick. The lighting comes from tiny shaded lamps on the walls.

The Wayfarers serves as restaurant and as pub - its short and reasonably priced wine list including English hard cider and several British beers and ales. Except for the service itself, it serves both functions very well.