Immediately across the road, the sign that hung in the window of La Lanterna restaurant said "fully booked". We told Sue we were dining there. "That will cost you an arm and a leg," was her parting shot.

For all sorts of reasons this is a restaurant which you enter determined to like. The owner Giorgio Alessio was broadcasting the virtues of local produce long before that bandwagon started rolling and he sticks to his principles. He's also very resourceful – any man who knows where to unearth truffles in the wilds of North Yorkshire, as he does, demands respect.

There used to be a restaurant beside the beach at Anzio on Italy's west coast where they took visiting journalists. It was nothing to look at, inside or out, but all the food was taken from the waves lapping a few yards away and it was sensational. Giorgio Alessio, who comes from Moncalvo in northern Italy, has made his reputation doing something along these lines in Scarborough. The sea isn't exactly on his doorstep, but he's down there on the quay each morning buying what is available.

The town in general seems to have forgotten the art of making the most of subtle and diverse fishy flavours and textures. Judging by what's on offer on and around the seafront, you'd think there was a local by-law which rules that fish may only be cooked and served after being dipped and fried in a thick jacket of flour and fat. On this Friday night the Lanterna specials list alone spoke loudly of Neptune's richer bounty – velvet crab, ling, woof, cockles, monkfish, halibut, wild sea bass, brill and turbot.

There's a story Sir Alan Ayckbourn tells from 1973 when, walking home after an evening show, he came across a rare sight – a restaurant open in Scarborough after eight o'clock. Having discovered La Lanterna, the playwright and his staff felt it their duty to keep it open and it remains in his eyes a "treasure". An assortment of of other theatrical knights such as Michael Caine have also left their mark here and their endorsement of Sir Alan's judgment. This is an owner-chef who is no stranger to the media. Framed reviews, interviews, features and other cuttings hang on most parts of the cream walls.

The welcome, warm and relaxed, lives up to the publicity. The service is friendly, attentive and expert. It was clear on this night that many customers, tending in the main towards later middle-age, were on conversational terms with the staff which made for an easy atmosphere.

It's pleasingly furnished, and Italian imports like a wall-mounted brass torture device (which turns out to be nothing more menacing that an old cork remover) and vineyard pickers' baskets don't really give it the stamp of rusticity. Think more on the lines of cosy high-class English tea room and you have the picture.

The typical male-dominated Italian restaurant tends to be a bit dramatic. Here an all-female front-of-house staff give the place a quieter charm. There's just an occasional bit of theatre when chef comes through to whip up an ordered zabaglione dessert in a copper pan.

There were 11 specials available as starters and main courses. By the time you had heard the last on the list, you had forgotten what came at the beginning. Plus they seemed to be working on the basis that if you needed to ask the price of a dish you couldn't afford it, since none was volunteered. Why not put up a blackboard with the information?

The big selling point is food cooked to order. The centrepiece of our meal turned out to be a wild sea bass, baked with fresh herbs, from the specials list. It was huge, and it arrived at the table in a condition that suggested the speed from oven to plate could not have been bettered in your own home. Here were first-rate ingredients perfectly-timed and immaculately presented. The fish was moist and toothsome and at £21.50 value for money.

The chef it seems does not limit his insistence on freshness to the briny. The Jerusalem artichokes for the soup (Tapiabo) with Gorgonzola cheese were from his allotment. It had a luscious, creamy texture but the cheese overwhelmed the slightly smoky, more delicate flavour of the artichokes. More successful was a starter of fish stew – pieces of ling, woof and baby halibut in a delicate, tomato-based sauce.

The test of an Italian restaurant is supposed to be the pasta. This is all hand-made here, but a dish of ravioli was underwhelming. There seemed so little distance between it and shop-bought that the price of £15.95 looked steep, bordering on precipitous.

Main dishes were served with broccoli florets, deep-fried in a light and crisp tempura batter; lovely leeks with a satin sheen (which suggested the allotment again) sautéed with wine, cream and ham; and new potatoes.

For dessert (eight more of these available on the invisible specials list), a crème caramel scored highly for its lovely creamy consistency. Baked pears and ice cream were a combination made in heaven.

With a modest half carafe of excellent house white, the bill for two was a shade under £80. Pricey, but not a whole arm and a leg. La Lanterna has won numerous awards. Is it a treasure as the country's foremost playwright insists? It depends how you define it.

The customers who concluded their evening by making multiple bookings probably would agree.

The evening ended as agreeably as it began with no sense of being hurried from table to exit.

One of those framed articles on the wall describes how the owner-chef got backing from the regional development agency to encourage a taste for the locally-caught mini velvet crabs. Apparently, they are greatly prized on the Continent where they boil them up and squeeze out the meat directly into their mouths. We, of course, resist such simplicity, preferring our snacks to come sealed in foil bags printed with the long lists of additives employed to make the contents palatable.

So let's keep cheering on Giorgio Alessio, a man deserving credit for swimming against the tide.

La Lanterna, 33 Queen Street, Scarborough, YO11 1HQ. 01723 363616
Vegetarian meals. Wheelchair access (not WC), music, air-conditioned.
Open: Monday to Saturday 7pm to 9.30pm.