Saint-Omer has all the charm of Arras and Bruges, its northern European rivals for the tourist pound, but has two clear advantages over both. As it's only 40km (25miles) southeast of Calais, it can be reached from London via Eurotunnel in under three hours, given a clear run. And it is much less well known - which may be why a townhouse can cost as little as £81,000.

Most arrivals speed past on the péage heading south with no idea that they are within miles of one of the undiscovered jewels of northern France. Saint-Omer lies in the cockpit of northern Europe and has been fought over for centuries. But it has escaped the effects of more recent hostilities, despite being the headquarters of Maréchal Foch during the First World War - the Victorian military hero Field Marshall Frederick Roberts, 1st Earl Roberts of Kandahar, VC, “Bobs” to his men, died there late in 1914, his passing marked by a blue plaque on the Rue Gambetta.

As a result there is none of the modern infill that makes Calais so dispiriting. Instead, there is virtually not a building in the centre of town - a network of streets mostly south of the main square, which is named after the same Maréchal Foch - that dates from after 1850. Most of the delightful three or four-storey townhouses, their flat façades wedged together on the narrow pavements, date from the previous two centuries, and many display their age prominently.

A number of houses, still with the original features and carvings and several of them à louer - to rent - are in clear need of restoration. This architectural legacy is a reflection of centuries of prosperity that began in the 1160s with the creation of a canal linked to the River Aa that made the town accessible by sea. That prosperity is also reflected by the huge 13th-century cathedral, which contains a list of bishops dating to the 6th century and the tomb of Saint Erkembode, who died in 734. He was known for his wandering and as the saint of disabled children; his tomb is covered with brightly coloured bootees laid there by supplicant parents.

Walk from the main square, which hosts a Saturday market vibrant even by French standards, down the Rue de Dunkerque, the main shopping street, and you reach the docks and the quai de commerce - less busy than in medieval times. Across from this are the picturesque Audomarois marshes, where much of the local produce is grown. There are several colleges, at least two shops selling musical instruments and a lot of restaurants and bars. One, the Brasserie Audomaroise, off the Place Foch, is a microbrewery producing typically Flemish concoctions made from rhubarb and chicory. And do not miss Chez Tante Fauvette, in Rue Sainte Croix, a tiny restaurant dedicated to producing the sort of recipes cooked by the chef's aunt of the same name.

Flemish influence in Saint-Omer is strong, both architectural, in the prevalent Dutch gables, and culinary. Aside from those curious ales, hearty cabbage, pork and melted cheese dishes predominate, along with carbonnade flamande, a beer-and-beef stew. And chips with everything.

The countryside is easily within reach, including the hill town of Cassel, 176m (577ft) above the flat fields and whose hill was the site of the famous rout suffered by the Grand Old Duke of York in 1793. A grim reminder of more recent wars is La Coupole, south of Saint-Omer, a huge fortification hewn out of the rock by Hitler's slave workers to be the launch pad of the V2 rockets that were to rain down on London.

A three-bed townhouse in Saint-Omer in need of renovation costs about £81,000 to £101,000, a habitable one £161,000 to £181,000. Detached three-bed houses within a ten-minute drive of Saint-Omer cost from £186,000 to £242,000. Within easy range for a day trip are the picturesque coastline and the towns of LeTouquet-Paris-Plage and St-Valéry- sur-Somme, and Arras itself inland.

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