For some reason the Romans neglected to overrun the country with fire and sword, though they had both of these; in fact after the Conquest they did not mingle with the Britons at all but lived a semi-detached life in villas. They occupied their time for two or three hundred years in building Roman roads and having Roman Baths, this was called the Roman Occupation, and gave rise to the memorable Roman law, 'He who baths first baths fast', which was a good thing and still is. The Roman roads ran absolutely straight in all the directions and all led to Rome. The Romans also built towns wherever they were wanted, and, in addition, a wall between England and Scotland to keep out the savage Picts and Scots.
(From 1066 and All That by C. W. Sellar, R. J. Yeatman)