Prix Fixe

Fun. If I had one word to sum up Prix Fixe, it's that giggly three-letter syllable that could do with more of an airing in restaurants. There’s a themed menu that changes each month and a commitment to quality without the seriousness that often goes with it. August is a whimsical Lion, Witch and Wardrobe affair, entered through a cupboard of furs, with a menu that tours jolly old England. The stepped dining room has a dramatic, stage-set feel, as though you're part of a comedy of manners called The Restaurant. Round tables dot the room; they always make conversation fun.

Chef Philippa Sibley's facility with classic flavours and techniques is consistent through menu shifts. This month her deft touch is ardently expressed in the celery soup, creamy and frothy with a depth of flavour thanks to celeriac, and the cheeky flourish of Stilton ice-cream. The set menu also includes gin-spiked cucumber sandwiches and fabulous braised lamb encased in suet pastry (suet is hard beef fat, used as a shortening, and it creates an absurdly rich crust).

You can take your luck and walk in but the bookings procedure is to buy a ticket from the restaurant’s website, just like the theatre. If you're sick or the babysitter bails the onus is on you. The obligation feels extreme in a dining culture where spontaneity and queuing are as popular as committing but I love it. One of my mates found he'd double-booked after we'd bought our tickets - it was relaxing to tell him to sort it out, rather than renegotiate our arrangement.

I imagine Prix Fixe is fun for Philippa Sibley too, partly because the ticket-to-dine modus expunges the constant niggle of no-shows, and because it must be fun (of a whirlwind, what-was-I-thinking sort) to reinvent the menu so frequently. The price may be fixed but the experience is free-wheeling and fabulous.

Rating: Four stars (out of five)