Roman I have chosen to begin the story of Britain in the year the Romans came, fifty-five years before the birth of Christ, over 2,000 years ago. Before Julius Caesar, the Roman Empire''s greatest general, led his first expedition ashore, the country''s stormy seas isolated her from the traffic of the European continent. Apart from her own inhabitants, no one knew very much about the place, though there were rumours. How far did it stretch north? Were its forests impenetrable? Was it really an island? Was its mineral wealth extraordinary? Since at least the fourth century before Christ, that is 250 years before Caesar appeared, the natives had been mining highly prized gold and tin for export at the Island of Ictis (St Michael''s Mount) on the extreme south-western tip of Britain, and they had trading links as far afield as the Mediterranean. As a result of this trade, in 300 BC the Greek colony of Massilia, or Marseilles, had sent one of its citizens named Pytheas on a reconnaissance trip to Britain. Pytheas had noted the friendly nature of the inhabitants. It was said that the Britons'' relations further east had some secret method of transporting vast blue stones from a more mountainous region. On a great plain north-east of their chief port in Dorset, they or perhaps their gods were said to have erected the enormous circle called Stonehenge which was used for religious ceremonies.

But Pytheas'' description is a mere fragment reported in a later work. Since the British tribes could not read or write, they remain as mysterious and fabled as their distant ancestors, the small, dark, long-headed Neolithic or New Stone Age invaders who started to arrive from the Mediterranean in 3000 BC. That British Neolithic man hacked at the soil with deer antlers to grow a little wheat, and that he used flint-headed arrows to kill game for food have had to be deduced from what archaeologists have found in their long barrow graves. It is only when we get to Caesar''s Commentaries on the Gallic War that we are able to read the first written description of the country known to the Romans for 400 years as Britain. By the time of Pytheas and Caesar himself the inhabitants of ancient Britain were mainly what have come to be known as Iron Age Celts. Like the Iberians in Spain and the Gauls in France, they were members of the great military aristocracy which until the rise of the Rome city state in the third century BC were masters of the trade routes between northern and central Europe and the Mediterranean. The Celts were the second wave of invaders to follow Neolithic man to Britain, but they came 2,000 years later, around 1000 BC. Between Neolithic man, whose great monument is the stone-circle temple at Avebury in Wiltshire, and the Celts another wave of invaders had arrived.

These invaders were round-headed Bronze Age people, originally from the Rhineland, who reached Britain in about 1900 BC. They were a stronger, larger race than Neolithic man, though still dark and swarthy, and they swiftly occupied England from the east coast of Yorkshire down to Surrey. This more sophisticated race is sometimes known as the Beaker People because of the drinking vessels found in their graves. They could make tools from bronze; they built Stonehenge; they buried their dead in individual round barrows. But in their turn about 1000 BC their way of life was challenged by a new, more powerful civilization. From the first millennium BC the Celts of eastern Europe were migrating west. The expansion of the Germanic tribes at their back encouraged them to move into northern and western Europe, particularly into France, Spain and Britain, bringing with them what is known as the Iron Age. Their peoples were sophisticated enough to known the secret of mining iron ore out of the ground - they could extract the iron ore by heating it.

Then they worked the more difficult metal by beating layers of it together. This enabled them to achieve a major advance on bronze or flint tools, and with their stronger iron spears they easily defeated the Bronze Age peoples. They could also travel faster in chariots furnished with iron wheels and drawn by horses that they loved so much they had them buried with them in their graves. Tall and fair skinned with red or blond hair and blue or green eyes, the Celts were not only physically quite dissimilar to Bronze Age man, they also spoke a different language. No one is quite sure why two kinds of Celtic languages developed. Goidel, from which comes the word Gaelic, was spoken in Ireland and Scotland, and Brythonic is the family from which Welsh, Breton and Cornish derive. Unlike the cave-dwelling Neolithic man, the Celts built their own huts with posts sunk in mud and woven branches for the roof. Although at first they lived in hill forts enabling them to command the countryside, they developed ploughs and were soon farming the surrounding land in small square fields, a shape that would continue through Roman times.

Some of those who settled in south-west England lived in lakeside villages, island-like enclaves designed for protection. The Celts were ruled by queens as well as kings, and might even be led in battle by women. By the first century BC Britain (or Britannia, as the Romans called it) had attracted Caesar''s hostile attention. He wished to put an end to the use of Britannia as a sanctuary by the leaders of Gaul (a country covering roughly the territory of modern France) rebelling against their Roman overlords. Archaeologists have shown that in the first century AD the inhabitants of Britain''s south coast, sailing from their chief port of Hengistbury Head in Dorset, had a great deal of trade with Gaul. Within Caesar''s lifetime southern Britain and northern France may have been ruled by a Gallic overlord called Diviacus. Caesar believed that the Britons'' powerful religious leaders, the Druids, were also helping to foment trouble. The rebellious Belgae in north-west Gaul, what is now Belgium, had close relations across the Channel in Britain to whom they were in the habit of fleeing in times of trouble.

These Belgae, who were now known as Catuvellauni after their leader Cassivellaunus, had settled there from Gaul within living memory. Making Britannia a province of the Roman Empire would finally break the power of the Belgae, whom Caesar was determined to destroy. It would also usefully add to his reputation as a great man by extending the empire even to the edge of the known world. Expanding the empire''s territories, rather than administering them, was how glory and power were won in the uniquely militaristic society of Caesar''s Rome. Gathering information about Britain''s harbours and landing places was one reason why Caesar sailed across the ''Ocean'' (the Channel) on his first expedition in 55 BC. He landed with some difficulty owing to a spring tide which swamped his heavy transport ships. He noted that the houses and inhabitants of Britain seemed very similar to those of Gaul, with the striking difference that rich or poor the British men were shaved of all bodily hair (except for the upper lip, where they grew long moustaches) and painted with a blue dye called woad. Their reddish hair was also worn very long, often with a headband.

They knew how to cure hides for export and had a good trade with the continent in iron, cattle and corn, using gold and iron bars in a rudimentary currency system. But as Caesar approached the shores of Kent at what is now Deal the woad-covered Britons looked wild and primitive as they whirled in their chariots on the cliffs above him. Because they wore skins Caesar assumed that they could have no knowledge of cloth-weaving, which to a Roman was one of the marks of civilization. But the ancient Britons'' appearance was misleading. They knew how to spin wool, how to weave it into garments and how to dye it with colours from flowers and insects. Indeed they usually wore long woollen tunics, cloaks and robes fastened by intricate articles of jewellery in swirling patterns which their talented smiths made out of gold, silver and enamel. They were half naked when they were first seen by Caesar only because that was their battle costume. Their Celtic relations, the Gauls across the channel, fought completely naked.

Caesar nevertheless continued to believe that, although the people of Cantium (his translation of the name he heard them use for their country - that is, Kent) were in fact fairly civilized and knew how to grow grain, Britons who lived further north did not know how to cultivate crops and lived on what they hunted. It was true that compared to Roman civilization, with its advanced precision engineering which enabled the Romans to build stone bridges, roads and aqueducts, its architectural science which threw up palaces and forts, its military and political science, the Britons seemed childlike, ignorant and superstitious. They were ruled by the white-robed Druids, who regarded mistletoe as sacred and practised human sacrifice, burning their victims in wicker cages. Hares, fowl and geese were also sacred, which meant they could not be eaten - although the Britons liked them as pets. The Britons were said to love poetry, but they were also extremely quarrelsome. Caesar found Britannia''s climate more temperate than that of Gaul, though much wetter, and by his water clock he could confirm that being further north the nights in this strange new country were shorter than on the continent. Moving inland he came upon a great river in the east of the country about eighty miles from the south coast which he called the Thamium, a Latin approximation of the name the ancient Britons gave to what we still know as the Thames. He was impressed by the bravery of the British warriors and by their methods of chariot warfare, describing t.