Holsworthy is a market town and civil parish in the Torridge district of Devon, England, 36 miles west of Exeter. The River Deer, a tributary …Holsworthy is a market town and civil parish in the Torridge district of Devon, England, 36 miles west of Exeter. The River Deer, a tributary of the River Tamar, forms the western boundary of the parish, which includes the village of Brandis Corner. According to the 2011 census the population of Holsworthy was 2,641, growing to an estimated 3,287 in 2019.