Morgan M, 50 Long Lane, London EC1

At a dinner shortly before Christmas, I was placed next to a fellow restaurant critic far more experienced than me. Shortly before dessert, I asked whether he felt there were any occupational hazards attached to this most privileged of occupations. The lady to his left instantly snapped at us: "The tendency to sound ungrateful." Indeed, what could be worse, than to eat at fine restaurants, be paid for it, and still come across as ungrateful? So it is with a heavy heart that I make this confession: there follows a report about Morgan M in which your correspondent answers very neatly to the lady's description.

It's a relative thing. The previous week, as long-suffering readers will know, I had been to Dabbous, an exceptionally good new opening in the centre of London, where there is a tasting menu for £50. At Morgan M, the same deal goes, but it can't compete. Therefore I am in the curious position of recommending this place but also saying that, for this price, there's markedly better elsewhere.

Morgan Meunier is a distinguished chef. For years his Islington redoubt served classic French cuisine with panache. He has now moved to a site opposite Smithfields market, where most of the passing trade will presumably come from City spillovers brandishing the company card.

There are two floors, ground and basement. We eat on the ground floor, where the décor is smart but stale, and shot through with a vanilla-and-pale-green hue. The chairs are comfortable and the cutlery is Robert Welch. There are five options beyond the tasting menu, but since prices vary from £21.50 for pheasant to £28.50 for lamb, it may be worthwhile going for the taster. There are two of those, in fact: both six courses, but the vegetarian one is £4 cheaper at £46.

Both start with cream of Mojette beans with lemon confit and pesto, which is excellent and very aromatic. One of the options to follow is a crayfish-and-lobster cannelloni with tarragon, Jerusalem-artichoke soubise (onion sauce) and a shellfish cappuccino. This last, foamy supplement coheres the whole plate, and the cannelloni is perfectly done. There is also a chunky, well-seasoned game terrine with foie gras, apple chutney and toast – all very seasonal and delicious.

Then there is a fillet of sea bass with carrot-and-ginger risotto, or, on the vegetarian side, an exquisite mushroom cannelloni with mushroom, garlic purée and broth. This is French cuisine at its halitosis-inducing finest, and the venison fillet with a spot of stuffed hare and quince purée that follows is very distinguished, too. The vegetarian option of beetroot with goat's cheese and pine-nut biscuit is unadventurous in comparison, but basically faultless.

Both menus then dive into a light vanilla rice pudding with orange tuile, a very thin and crisp cookie. The rice pudding is indeed light, but by this point we are on the verge of saturation, with dessert still to come. A serving of double carbs, however small, is unwarranted.

All the more so, as the desserts are superb. There is a passion-fruit soufflé and sorbet with a punchy crème anglaise, which feels about one course too late, because it is. Or there is a dark-chocolate moelleux (fondant, basically) with a milk sorbet. You can choose whether you have 45 per cent or 70 per cent chocolate, an ideal touch to lift the spirits at the end of a long meal. The moelleux is beautifully cooked; soft, inviting and not too heavy.

You can get wines with each course for £30, or £27.50 excluding dessert wine. The service, which is Gallic to the bone, is charming enough; but our waiters have suffered from not having enough to do, because even tonight, a Friday, the place is curiously empty.

Why this should be I cannot say. Morgan M has the hallmarks of a potentially great restaurant. The chef is a rare talent, the menu is mostly well-crafted and affordable to City types, and the location should guarantee regular, well-heeled visitors. The décor is a little forbidding, and maybe it will take a bold, lunchtime menu, or a radical discount on the tasting menus, to start drawing in the punters and generate the sort of buzz that a new Morgan M deserves.

Until that alchemy is magicked up, this place will be the preserve of the ungrateful. Happily, it needn't be that way for long.

7/10

Scores: 1-3 stay home and cook, 4 needs help, 5 does the job, 6 flashes of promise, 7 good, 8 special, can't wait to go back, 9-10 as good as it gets

Morgan M 50 Long Lane, London EC1, tel: 020 7609 3560 Lunch and dinner, Mon-Fri; dinner, Sat. About £350 for four, including wine

Gallic gods

Galvin La Chapelle

35 Spital Square, London E1, tel: 020 7299 0400

The Galvins' spectacular Spitalfields yearling is a beautifully sympathetic conversion of a high-vaulted Victorian school hall offering impeccable, inventive brasserie fare

Les Trois Garçons

1 Club Row, London E1, tel: 020 7613 1924

Don't be put off by the stuffed animals – they form part of the magical setting at this quirky East End pub conversion; the Gallic cuisine plays second fiddle, but it's better than you might expect

Boundary

2-4 Boundary Street, London E2, tel: 020 7729 1051

Sir Terence Conran's cool Shoreditch basement offers faultless brasserie-style fare (although it's not cheap)

Reviews extracted from 'Harden's London and UK Restaurant Guides 2012' www.hardens.com