Sudbury is a market town in the south west of Suffolk, England, on the River Stour near the Essex border, 60 miles north-east of London. At …Sudbury is a market town in the south west of Suffolk, England, on the River Stour near the Essex border, 60 miles north-east of London. At the 2011 census, it had a population of 13,063. It is the largest town in the Babergh local government district and part of the South Suffolk constituency.