 The earliest reference to the town is in the Anglo @-@ Saxon Chronicle , which records that in 733 the King of Wessex , Æthelheard lost control of Somerton to Æthelbald , King of Mercia . Somerton was the site of the 949 meeting of the witan , a form of Anglo @-@ Saxon parliament . The town returned to West Saxon royal control in the ninth century , and it was listed in the Domesday Book of 1086 as " <unk> " . The name may come from Old English for " sea @-@ lake enclosure " , " summer town " or " summer farmstead " . The Somerton name was extended to the people in the area it controlled , and this area became known as Somerset , although Somerton soon ceased to be the most important settlement and never grew into a large town . The parish was the largest in the Hundred of Somerton . It was , briefly , the county town of Somerset from the late thirteenth century into the early fourteenth century . A building referred to as " Somerset castle " is believed to have been built around 1280 as a county gaol , with a visitor in 1579 describing the remaining portion as " an old tower embattled about castle @-@ like " . It was owned by Sir Ralph Cromwell between 1423 and 1433 . Details are vague and visible remains have vanished , so its status as a castle and its very existence is in doubt , with one writer , <unk> King , feeling that people were confusing it with Somerton Castle in Lincolnshire . 
