Behind these formidable garrisons, sheltered from barbarians and in easy contact with the Roman empire, stretched the lowlands of southern and eastern Britain. Here a civilized life grew up, and Roman culture spread. This part of Britain became Romanized. In the lands looking on to the Thames estuary (Kent, Essex, Middlesex) the process had perhaps begun before the Roman conquest. It was continued after that event, and in two ways. To some extent it was definitely encouraged by the Roman government, which here, as elsewhere, founded towns peopled with Roman citizens - generally discharged legionaries - and endowed them with franchise and constitution like those of the Italian municipalities. It developed still more by its own automatic growth. The coherent civilization of the Romans was accepted by the Britons, as it was by the Gauls, with something like enthusiasm. Encouraged perhaps by sympathetic Romans, spurred on still more by their own instincts, and led no doubt by their nobles, they began to speak Latin, to use the material resources of Roman civilized life, and in time to consider themselves not the unwilling subjects of a foreign empire, but the British members of the Roman state. The steps by which these results were reached can to some extent be dated.

Within a few years of the Claudian invasion a colonia, or municipality of time-expired soldiers, had been planted in the old native capital of Colchester (Camulodūnum), and though it served at first mainly as a fortress and thus provoked British hatred, it came soon to exercise a civilizing influence. At the same time the British town of Verulamium (St Albans) was thought sufficiently Romanized to deserve the municipal status of a municipium, which at this period differed little from that of a colonia. Romanized Britons must now have begun to be numerous. In the great revolt of Boadicea (60) the nationalist party seem to have massacred many thousands of them along with actual Romans. Fifteen or twenty years later, the movement increases. Towns spring up, such as Silchester, laid out in Roman fashion, furnished with public buildings of Roman type, and filled with houses which are Roman in fittings if not in plan. The baths of Bath (Aquae Sulis) are exploited. Another colonia is planted at Lincoln (Lindum), and a third at Gloucester (Glevum) in 96. A new "chief judge" is appointed for increasing civil business. The tax-gatherer and recruiting officer begin to make their way into the hills.

During the 2nd century progress was perhaps slower, hindered doubtless by the repeated risings in the north. It was not till the 3rd century that country houses and farms became common in most parts of the civilized area. In the beginning of the 4th century the skilled artisans and builders, and the cloth and corn of Britain were equally famous on the continent. This probably was the age when the prosperity and Romanization of the province reached its height. By this time the town populations and the educated among the country-folk spoke Latin, and Britain regarded itself as a Roman land, inhabited by Romans and distinct from outer barbarians.

The civilization which had thus spread over half the island was genuinely Roman, identical in kind with that of the other western provinces of the empire, and in particular with that of northern Gaul. But it was defective in quantity. The elements which compose it are marked by smaller size, less wealth and less splendour than the same elements elsewhere. It was also uneven in its distribution. Large tracts, in particular Warwickshire and the adjoining midlands, were very thinly inhabited. Even densely peopled areas like north Kent, the Sussex coast, west Gloucestershire and east Somerset, immediately adjoin areas like the Weald of Kent and Sussex where Romano-British remains hardly occur.

The administration of the civilized part of the province, while subject to the governor of all Britain, was practically entrusted to local authorities. Each Roman municipality ruled itself and a territory perhaps as large as a small county which belonged to it. Some districts belonged to the Imperial Domains, and were administered by agents of the emperor. The rest, by far the larger part of the country, was divided up among the old native tribes or cantons, some ten or twelve in number, each grouped round some country town where its council (ordo) met for cantonal business. This cantonal system closely resembles that which we find in Gaul. It is an old native element recast in Roman form, and well illustrates the Roman principle of local government by devolution.

In the general framework of Romano-British life the two chief features were the town, and the villa. The towns of the province, as we have already implied, fall into two classes. Five modern cities, Colchester, Lincoln, York, Gloucester and St Albans, stand on the sites, and in some fragmentary fashion bear the names of five Roman municipalities, founded by the Roman government with special charters and constitutions. All of these reached a considerable measure of prosperity. None of them rivals the greater municipalities of other provinces. Besides them we trace a larger number of country towns, varying much in size, but all possessing in some degree the characteristics of a town. The chief of these seem to be cantonal capitals, probably developed out of the market centres or capitals of the Celtic tribes before the Roman conquest. Such are Isurium Brigantum, capital of the Brigantes, 12 m. north-west of York and the most northerly Romano-British town; Ratae, now Leicester, capital of the Coritani; Viroconium, now Wroxeter, near Shrewsbury, capital of the Cornovii; Venta Silurum, now Caerwent, near Chepstow; Corinium, now Cirencester, capital of the Dobuni; Isca Dumnoniorum, now Exeter, the most westerly of these towns; Durnovaria, now Dorchester, in Dorset, capital of the Durotriges; Venta Belgarum, now Winchester; Calleva Atrebatum, now Silchester, 10 m. south of Reading; Durovernum Cantiacorum, now Canterbury; and Venta Icenorum, now Caistor-by-Norwich. Besides these country towns, Londinium (London) was a rich and important trading town, centre of the road system, and the seat of the finance officials of the province, as the remarkable objects discovered in it abundantly prove, while Aquae Sulis (Bath) was a spa provided with splendid baths, and a richly adorned temple of the native patron deity, Sul or Sulis, whom the Romans called Minerva. Many smaller places, too, for example, Magna or Kenchester near Hereford, Durobrivae or Rochester in Kent, another Durobrivae near Peterborough, a site of uncertain name near Cambridge, another of uncertain name near Chesterford, exhibited some measure of town life.