Interior of Church of St Gregory, Kirk Newton : P F Ryder

The internal walls of the 19th century parts of the church are plastered, with the exception of exposed dressings, and also the westernmost part of the north wall of the north aisle which is of exposed roughly-coursed quite small rubble. The south porch has a stone bench set against the west wall, and a common rafter roof with scissor braces and ashlaring. A two-centred doorway with a chamfered surround, and a rear arch of flattened segmental-pointed form, gives access to the main body of the church.

Within the Nave the four-bay north arcade has two-centred arches, each of one broad chamfered order, on octagonal piers and semi-octagonal responds with moulded capitals and bases. Although the NCH states that the lower parts of the piers are genuine medieval work (and Wilson's plan shows that a blocked arcade of the present form was present in the north wall of the pre-1860 nave) all the visible fabric looks of the mid 19th century.

The lancet windows in the west end have plain pointed rear arches, but all the others in the nave and aisle have shouldered heads to their internal openings. The tower arch, at the west end of the aisle, is of two-centred form and of two chamfered orders, the inner dying into the jambs but the chamfer of the outer continued down to floor level; it contains a late 20th-century wooden screen with a two-centred doorway and a roundel above containing 19th century? heraldic glass. The nave roof is of common rafter type with collars and scissor bracing, with ashlaring to the eaves.

The arch to the South Transept is of two-centred form and of two chamfered orders, springing from plain square jambs (of 19th-century ashlar in their present form) with large impost blocks chamfered on their lower angles. The slab floor of the transept is set one step below that of the nave and it is covered by a vault of two-centred section, springing from ground level, and covering by roughcast or harling. The only old feature is a piscina at the east end of the south wall, with a four-centred arch and a bowl within the thickness of the wall.

The arch into the Chancel is rather similar to that into the transept; it is of segmental-pointed form and two chamfered orders, resting uncomfortably on plain square jambs with heavy impost blocks chamfered on their lower angles. The jambs are plastered towards the nave but left bare towards the chancel. The chancel has a vault, similar to that of the transept but sprinting from c 1 m above the floor rather than from ground level; much of it is roughcast but there are areas of exposed stonework; sections would appear to have been rebuilt in the 19th century. The rough segmental rear arches of the priest's door and south window cut into the haunch of the vault; the head of the latter could well be a 19th-century reconstruction, as its sill certainly is.

There is a disturbed area midway along the north wall of the chancel.

Built into the east wall of the nave to the north of the chancel arch is a sculptured panel showing the Adoration of the Magi, an attractive but markedly rustic piece of work that is probably Romanesque, ie 12th century. In the opposite face of the same wall (i.e. facing towards the chancel), partly concealed by mortar, is a stone with a net-like pattern in relief that may also be of 12th-century date, as may a headstone (?) in the south transept that has a carving of a figure holding a cross. Also in the transept is a slab with the incised effigies of Andrew Burrell (d.1458) and his wife; their heads and hands have been inlaid in brass, now removed.