The fort of Hayton, south-east of Pocklington, North Humberside (Yorkshire), was first located from the air by Professor J. K. St. Joseph in 1974. His photographs showed a small fort surrounded by double ditches: the crop-mark of these was distinct on the SE, NE and NW sides (PL. IX) and at the rounded northern and eastern angles. Further reconnaissance in 1975 produced more photographs which introduced the possibility that the fort also had an annexe to its north-east. A single ditch appears to continue the line of the inner fort ditch on the south-eastern side and form an enclosure with rounded angles to the north-east of the fort. Examination of Ordnance Survey photographs taken in 1968 showed that the platform of the fort had been just visible then. In view of the sudden clarity of the fort cropmarks, it was decided to undertake a small-scale excavation to discover whether the remains of the fort were being eroded by the constant ploughing to which thearea is subject. The first campaign, in February 1975) took place in the field south of the minor road which runs through the fort site (FIG. I, Areas A–F) and located the eastern angle, parts of the angle-tower and the south-east gateway. A second season, in October and November of the same year, examined the state of preservation of the remains in the northern field after removal of the crop (FIG. I, Areas G–S) locating the line of the ditches on the three remaining sides as well as the north-east gateway, the north angle-tower and remains of two of the interior buildings.