La Bonne Étape, Château-Arnoux

France once ate its way south. The old holiday roads, the Nationale 7 above all, were lined with grand dining rooms where families pulled over for lunch and lingered until the coffee went cold. Many of those roadside temples have since gone modern, and some have gone altogether. La Bonne Étape, on the Route Napoléon at Château-Arnoux, has done neither. It is still a smart, old-fashioned dining room by the road, the kind of place where travellers stop for no better reason than to eat extremely well.

The family has kept the post house since 1911. Jane Gleize now runs the kitchen and writes the menus with her father Jany, the latest of four generations at the same stoves. Neither shows the slightest interest in being fashionable, and neither needs to, because the regulars come back for dishes they have been ordering for years. Father and daughter own up to the odd disagreement across the generation gap. Their joint cookbook is called Cuisine provençale d'aujourd'hui, Provençal cooking for today, and the title could serve as the house motto.

From outside, the inn looks much as a coaching stop should, solid and a little stern. Inside it softens into something like a well-kept family sitting room, a touch formal but never cold. The eighteen rooms feel lived in rather than styled. Dogs are as welcome as their owners, and the house dog makes a point of inspecting each new arrival. The outbuildings have found new work too, with the kitchen in what were the stables and the swimming pool where the laundry used to be.

Just before dinner, the chef can sometimes be found in the herb garden by the kitchen door, among the thyme and the savory. There is always time to explain what each plant will do on the plate, and the same herbs reappear later in almost every course. Few hotels offer a briefing that smells this good. In summer the garden also supplies the courgette flowers that come to the table stuffed.

Dinner is served upstairs, on what was once the threshing floor. The cooking is Provençal family food, refined over decades rather than reinvented each season, with olive oil from Les Mées. Lamb from Sisteron, the next town up the valley, comes roasted with a tian of vegetables, and nobody would dare take it off the menu. The finale is an ice cream of lavender honey, served in its own little hive. On a second night, Bistro Gaby, the family's bistro, offers a simpler version of the same cooking.

Old school has its drawbacks too. Château-Arnoux is more practical than picturesque, and the great lavender fields around Valensole lie a fair drive to the south. Diners in search of the latest techniques will find none of them here, and that is entirely deliberate. On an off night not every dish lands, and service can vary with the shift.

Napoleon came up this road on his way back from Elba and never stopped. It remains one of his less forgivable mistakes.