MANY worse things can be said of a restaurant than that it is useful; it is an underrated quality. Surpassing usefulness is a rare feat, especially in the West End of London. Le Palais du Jardin, a six-month-old Covent Garden brasserie, has a silly name, but it is useful. It is open from 9am to midnight, it is clean and affordable, the food is (mainly) fine and the service good.

Clockwork professionalism is seasoned with touches of glamour, and an oyster bar-cum-cafe at the entrance invites Continental-style lingering. In a large dining room at the back, the napery is sturdy, the glasses delicate. Red roses adorn each table.

There are no weird flights of imagination on the menu, but when the cooked article is set before you, it will probably be competently prepared. The scallops with spinach and bacon certainly were. Two discs of goat's cheese baked on little croutons were even better.

There might be slips, however. A fish cake involving shrimp, cod, smoked haddock and salmon tasted unpleasantly fishy, as if its constituents had been landed at Whitley Bay, and made it to the restaurant via a fish-finger factory. (The management reports that the fish cakes have since been overhauled.) Steak tartare was better, but lacked balance. It tasted more of tabasco than meat, and thin chips were pale, greasy and lank.

If the raw ingredients are as good as they look, the oyster bar is a boon. A lobster is pounds 12; six Pacific oysters, pounds 4.75; six Natives, pounds 6.50. Other nibbles on offer are just as keenly priced: beef carpaccio, pounds 4.95; guacamole and smoked chicken, pounds 3.75.

The starter-orientated menu owes a lot to the young chef, Winston Matthews, who used to cook at Menage a Trois, where the gag was an entire menu of starters. Here the gimmick is brought to book and usefully deployed. Along with snacks, there are breakfasts and cream teas.

COMPARED with Le Palais du Jardin, The Ark, a chain of two restaurants set at opposite ends of Kensington Church Street in London, is an old chestnut. The branch just off Notting Hill Gate, known as the 'baby Ark', is 30 years old. It proved so popular that 25 years ago it spawned the 'big Ark', a handsome place just off Kensington High Street.

Times have changed since either Ark was a good bet for salmon steak with hollandaise sauce and a sprig of dill. Perhaps to keep pace, the big Ark has employed a new chef, Michael Forster from Le Caprice, and new manager Suzanne Roberts. Reports have come in from readers that the new regime produces good food and serves it graciously. My experience was different, and almost wholly unhappy. It emerged later that on the night we ate, both the new chef and new manager were off.

Here is what was produced in their absence: as a starter, the Jerusalem artichoke tart had a reasonable creamed filling, but the base of the shortcrust was raw. Not undercooked. Raw. The waiter suggested it simply might have absorbed oil poured over the salad that accompanied it. This was scant consolation, and he was wrong.

The confit of rabbit was dry and inedibly salty. The waiter - he of the shortcrust - deducted it from the bill after informing us that it 'may have been too salty for someone who does not like salt'. Dessert - three-chocolate mousses - came with a curious garnish: a large dollop of whipped cream, sliced apple and a leaf of mint.

There is a cover charge, presumably to cover some bog-standard bread rolls, of pounds 1 each. A meal including two kirs, a half bottle of pounds 6.75 sauvignon blanc, a bottle of mineral water, two starters, two main courses, one dessert and one coffee cost pounds 48.45, before service. If it is true that the dusted-down Ark usually sends out good food, then this would be fair; it was not for our meal. To be useful, you have to achieve the same good standards every day.

Le Palais du Jardin, 136 Long Acre, London WC2 (071-379 5353). Children welcome; special portions on request. Vegetarian meals. Wheelchair access (also w c). Piped jazz. Open daily: breakfast, 9am-12noon; lunch, 12noon-3.30pm (a la carte menu plus oyster bar); 3.30pm-5.30, oyster bar and cream teas; dinner, 5.30-12midnight last orders, 11pm on Sundays. Major credit cards.

The Ark, 35 Kensington High Street, London W8 (071-937 4294). Vegetarian meals. Open: lunch, Mon-Fri, 12noon-3pm; dinner, Mon-Sat, 7pm-11.15pm (nightly after Easter). Major credit cards.

(Photograph omitted)