Strabo, the Greek geographer who lived between 44 BC and AD 23, wrote of Iron Age Britain ......

Book IV Chapter 5

Most of the island is flat and overgrown with forests, although many of its districts are hilly. It bears grain, cattle, gold, silver, and iron. These things, accordingly, are exported from the island, as also hides, and slaves, and dogs that are by nature suited to the purposes of the chase. The men of Britain are taller than the Celti (the people across the English channel), and not so yellow-haired, although their bodies are of looser build. The following is an indication of their size: I myself, in Rome, saw mere lads towering as much as half a foot above the tallest people in the city, although they were bandy-legged and presented no fair lines anywhere else in their figure. Their habits are in part like those of the Celti, but in part more simple and barbaric — so much so that, on account of their inexperience, some of them, although well supplied with milk, make no cheese; and they have no experience in gardening or other agricultural pursuits. And they have powerful chieftains in their country. For the purposes of war they use chariots for the most part, just as some of the Celti do. The forests are their cities; for they fence in a spacious circular enclosure with trees which they have felled, and in that enclosure make huts for themselves and also pen up their cattle — not, however, with the purpose of staying a long time. Their weather is more rainy than snowy; and on the days of clear sky fog prevails so long a time that throughout a whole day the sun is to be seen for only three or four hours round about midday. 

The Deified Caesar crossed over to the island twice, although he came back in haste, without accomplishing anything great or proceeding far into the island, not only on account of the quarrels that took place in the land of the Celti, among the barbarians and his own soldiers as well, but also on account of the fact that many of his ships had been lost at the time of the full moon, since the ebb-tides and the flood-tides got their increase at that time. However, he won two or three victories over the Britons, albeit he carried along only two legions of his army; and he brought back hostages, slaves, and quantities of the rest of the booty. At present, however, some of the chieftains there, after procuring the friendship of Caesar Augustus by sending embassies and by paying court to him, have not only dedicated offerings in the Capitol, but have also managed to make the whole of the island virtually Roman property. Further, they submit so easily to heavy duties, both on the exports from there to Celtica and on the imports from Celtica (these latter are ivory chains and necklaces, and amber-gems and glass vessels and other petty wares of that sort), that there is no need of garrisoning the island; for one legion, at the least, and some cavalry would be required in order to carry off tribute from them, and the expense of the army would offset the tribute-money; in fact, the duties must necessarily be lessened if tribute is imposed, and, at the same time, dangers be encountered, if force is applied.