Latium is so self-effacing that I very nearly missed it in London's Berners Street. It occupies a space opposite the Sanderson hotel, and it is as understated in its design (but not chilly) as Sanderson hotel is overstated (and, consequently, rather baroque in a dead cool kind of way). The floor is slate grey. The walls are white. On them are large photographs of food, printed with the colours slightly leached out of them. And that's it. You can't get more understated than that. But the place bustles, and there is the food on the plate to put a zip back into lunch.

As the name suggests, the unique selling proposition of Latium is that it serves the food of the home region of chef Maurizio Morelli, Lazio, that rather flat bit of Italy around Rome. To be honest, I'm not quite sure what the distinguishing features of la cucina laziale are, and I wonder a little what some of Signor Morelli's compatriots would make of his dishes. As in most Italian restaurants in London, the dishes at Latium are constructed along Franco-British lines - ie, they have sauce and vegetables - rather than along Italian lines, where, in my experience, the main ingredients usually come naked to the plate - ie, without sauce, vegetables or decoration of any kind. In Naples recently I ordered some salsicce as a meat course, and that's exactly what I got - two sausages on a plate. Ah, but such sausages. There is another sausage universe out there.

But I digress.

Tucker was in puckish mood. He wanted polipetti affogati, scarola e salsa di ceci, or stewed baby octopus with escarole lettuce and chickpea sauce to those without an Italian degree. In fact, blow the Italian for the time being or this review will never get going. After that he wanted a dish of the day, cod on mash with green beans. I wanted the full Italian experience: salad of veal tongue with celery and tuna sauce; selection of seafood ravioli with bottarga (dried tuna roe); stewed belly pork with radicchio, saffron mash and red wine sauce; and then cheese.

I loved my veal tongue almost as much as I loved the belly pork. The slices of the former were as limp as a silk handkerchief, swathed in a green sauce in which the mild muskiness of tuna and the gentle freshness of celery were well matched. There was also a neat stack of crunchy celery strips by way of contrast. It was a dish of elegant comfort. The stewed belly pork was anything but. The meat came in nutty nuggets tucked inside the bitter radicchio. The rugby balls of mash were vivid with saffron and carried the pungent, almost acid, flavour of the spice. And the red wine sauce was a serious, potent reduction. In spite of quite a fetching presentation, it was not a suave dish. It was hefty and earthy. If they really do eat like this in Lazio, then they eat pretty damn well.

Sandwiched between these courses had been the ravioli of seafood which, when it came - four ravioli, one each of black, green, yellow and red - I had been tempted to dismiss as a piece of flummery. On closer acquaintance, however, I had to revise my view. The pasta was good, and each raviolo was quite distinct in flavour from its neighbour. It was quite a fancy piece of cooking.

I finished with a plate of cheeses, toma and pecorino sardo, which were about as good as they get, with slices of very ripe pear to go with them. It was, all in all, a very satisfying lunch.

I am not sure that Tucker's was in the same class. His baby octopus salad was decent enough, with tender gastropod and frilly tentacles in a nice brown stew, but the escarole didn't have the bitterness to lift the dish, and I am not sure that ultra-refined chickpea purée quite sets the pulses racing. And cod with mash is about as standard as you can get. It was good cod, and nicely cooked, and the potatoes, which had been crushed rather than mashed, were, well, crushed potatoes, mixed in with something green which made them look very pretty but, as Tucker couldn't pin down the flavour of the green stuff, seemed not to contribute much. And that was it for him. I forgave him because he was in the middle of a sequence of pre-Christmas bun fights and had to keep some fire power in reserve.

It turned out that Latium is not quite as self-effacing in the matter of bills as it is in the matters of self-promotion. You get two courses for £19.50, three for £23.50 and four for £28. So we managed a bill of £85, of which around £35 went on wine and water. I should add that the wine list is both exceptionally interesting and not greedily priced. All in all, I think Latium makes a decent enough addition to the list of regional Italian restaurants already in London.

Telephone: 020-73239123
Address: 21 Berners Street, London W1
Open: Mon-Sat, 12 noon-3pm; 6.30-10.30pm
Menus: lunch and dinner, £19.50 for 2 courses, £23.50 for 3, £28 for 4. Wheelchair access (no WC).