Somerset was already a well-organised county by the time the Normans invaded in 1066. Despite their military superiority, the Normans did not find subduing England an easy task and to keep an eye on the potentially rebellious populace, strong castles were built in various places across the land. Somerset"s share of castles stood at Montacute, Dunster and Neroche. Later, by 1135, more had been constructed at Stogursey, Castle Cary and East Harptree. At the same time, the Norman aristocracy took over the Saxon noble estates and by the year of the Domesday Book, 1086, there were only about seventy-five Saxon landholders. The King was the major landholder and what remained was divided up between forty-four Norman tenants-in-chief and their own tenants. The feudal system introduced by the Normans reorganised peasant life, but did little to improve their day to day existence. There were many unfree tenant farmers, owning about 16 hectares of land apiece, a larger number with even smaller holdings and an increasing mass of landless wage-earners.

Their difficulties increased as the population grew and extreme measures were taken to obtain new land for cultivation. Marshes and wetlands were drained to make meadow and pasture, hill land and salt grasslands were reclaimed, and woodland was cleared. By 1240 an extra 400 hectares had been freed but more was needed and earth and stone banks were constructed to reclaim the salt marshes around the River Parrett estuary. Reclamation could involve regular contests with the sea, which flooded in at times of unusually high tides,as happened in 1259. This seeming disaster had its "up" side, however, producing particularly fertile land once the floodwaters had receded. This, in its turn, produced plenty of taxes for the royal revenues which in the mid-14th century made the Stretcholt tithing in Pawlett, much of it consisting of reclaimed land, one of the most highly taxed in Somerset.

Agriculture in late medieval Somerset operated on both the mixed farming system and by open-field farming on land held in common with others. To ensure there was no trespassing, an "umpire" wearing white gloves and carrying a white stick was noted in 1340 supervising the mowing and the making of hayricks at Shepton Beachamp. Where there were no fields suitable plots of land, like closes, were used for planting oats and rye. The produce of manor orchards included fruit, especially pears and apples, some of which was turned into cider, vegetables such as leeks and onions and trees for timber.

Timber was a vital resource, used for houses, hurdles, furniture, tools and, of course, for fuel. Special grants of wood from the royal forests and parks were made for building purposes to the castles of Bridgwater and Stogursey, the abbeys constructed at Glastonbury and Cleve and for the prison at Somerton.

The mixed farming system employed many different agricultural specialists - drovers, oxherds, shepherds, swineherds and dairy workers. Somerset became well known for the quality and quantity of its butter and cheese and several estates had specialised dairies. The Abbey dairy at Galtonsborough, for instance, produced over 300 cheese and 77 kgs. of butter before beating its own record in 1304 with 406 cheeses and 102 kgs. of butter. Cheese made from goat's as well as cow's milk was also produced and large flocks of sheep were kept for the production of wool.