Mayfair's swishest club has opened its doors to non-members - even those humming Mick Hucknall songs. Photographs by Morley von Sternberg
However much media degenerates like myself might cherish our memberships of Groucho's or the Soho House, we must face the fact that there are great chunks of London clubland which will for ever remain closed to us. The streets of Mayfair and St James are stiff with liveried doormen, guarding imposing, nameless buildings where captains of industry gather in leather armchairs to doze, or moan about the degenerates who work in the media.

Morton's in Berkeley Square is one such enclave, complete with doorman and strict members-only policy, although it isn't a traditional gentleman's club, but an altogether racier kind of place. Its clientele is drawn from the loucher end of the Establishment - raffish financiers, the grander sort of advertising man - and I've always imagined it to be the kind of place Andrew Neil might have taken Pamella Bordes on their first date.

Now, though, anyone can swan past the doorman of Morton's. The first- floor club room has been converted into a fine new restaurant which is open to all-comers, provided they have a reservation and a robust bank balance. Michelin-starred chef Gary Hollihead, previously at Marco Pierre White's MPW in Canary Wharf, has been lured over to create what he promises will be a "great restaurant in probably the finest location in London".

The downstairs bar remains members-only, but my companion Tony and I were confident that as soon as the Morton's management spotted the stylish cut of our jib, we would be allowed to penetrate it at some point during the evening. We arrived with an 11pm reservation, to be met by a pin-striped gentleman who greeted us suavely with, "And how was the theatre?" Blushingly, we were forced to admit that we'd actually come from a Simply Red gig, immediately blowing the sophisticated image we needed to project if we were to glimpse the club's tantalising private recesses.

The elegant dining room has been redesigned with an updated Thirties feel by one of the owners of Morton's, Simon Lowe. Despite its high ceiling and the massive age-stippled mirrors that line the walls, the room has a pleasantly intimate town-house feel, with tall windows giving wonderful views over leafy Berkeley Square, clear across to the Rolls-Royce showroom.

Freed from the constraints of MPW's haute-brasserie approach, Gary Hollihead has devised an adventurous menu, featuring classic French dishes with an idiosyncratic twist. The serious accomplishment of his new kitchen was immediately obvious from the quality of the complimentary extra dishes that arrived before our starters - a basil-bright tomato consomme with langoustine for me; a vivid pea and mint soup for Tony.

Our starters maintained the high standard. My terrine of foie gras, containing a single sweet scallop at its heart, was a model of cool refinement, complicated by the elemental musk of shaved truffles. Tony's pave of tuna topped with a tangle of salad leaves was less chunky than "pave" might imply. "It's sliced so thinly that it melts even before it's in your mouth," Tony said. His dish, too, featured scallops in an unexpected guise, this time battered like scampi balls. The resulting combination of light and heavy flavours, was, he pronounced, "bewitching".

As we finished our starters, our fellow diners were gradually filing out, table by table, and we began to realise that though Morton's, the club, is a notorious after-hours hangout, Morton's the restaurant keeps soberer hours. Like the only customers in the Marie Celeste dining room, we maintained a brittle attempt at sophisticated chit-chat, our efforts resounding shamingly round the echoing room. To their credit, the all- male waiting team were relaxed and charming, betraying no sign of impatience at their Hucknall-tainted late arrivals, even when we abandoned the chit- chat and launched into an a capella reprise of "Fairground".

Tony had requested something light as a main course, exhausted as he was by an evening of vigorous frugging, and was consequently a little overwhelmed by the busyness of his etuvee of turbot and shellfish. He concentrated on the fish, which was plainly and perfectly cooked, and merely tinkered with the supporting cast of mussels and langoustines in a luxuriously creamy chive sauce. A bulbous stuffed courgette flower, however, he rejected altogether, mysteriously claiming that it was frightening him.

My own John Dory, roasted in a crust of 14 different spices, was an exercise in well-judged contrasts - the aromatic sweetness of caraway and fennel seeds cut through by the pleasant bitterness of a bed of braised endives. Tiny tomatoes and mango squares added dramatic notes of colour and flavour, and I found they worked extremely well with the stuffed courgette flower I helpfully liberated from Tony's plate.

The theme of restrained experimentation continues through the dessert menu. My brioche ravioli of chocolate saffron - light, fried puffs stuffed with smooth, dark chocolate - was like a dream of a child's birthday treat. Tony's lemon chiffon pie, on the other hand, was definitely one for the grown-ups - a crisp lattice- work windbreak of biscuit shielding a tantalisingly tangy tower of lemon mousse. Again, it seemed like an act of kindness to finish it off for him, when he proved unequal to the task.

Excluding wine, but including coffee at a cheeky pounds 2.75 a cup, our meal came to around pounds 50 a head - Mayfair prices, but Rolls-Royce cooking. By the time we were ready to leave, we had abandoned the Simply Red back catalogue in favour of an assault on Pilot's greatest hits. On the way out, we passed the door of the club bar, and I peeked behind it briefly, to glimpse a dark, noisy room heaving with suited gents and their elaborately groomed companions. We didn't attempt to force an entry - we'd had a great meal, and that was enough. And if you happened to be near Berkeley Square the other night and heard singing, I can only apologise. It wasn't a nightingale, just a couple of very happy diners, heading for the Groucho Club

Marco Pierre White's other rising young proteges: Bites, page 60

Morton's, The Restaurant, 28 Berkeley Square, London W1 (0171-493 7171). Lunch weekdays noon to 2.30pm, dinner Mon-Sat 7pm-11.30pm, Sun 7pm-10pm. Limited disabled access. All credit cards.