A small Norman church. Weather-boarded bell-cote over W end of nave; S aisle (early 13thc.; rebuilt c.1860) with Romanesque S doorway within gabled projection; chancel and N vestry (Victorian).

Tortington was not mentioned in the Domesday Survey, and is thought to have been built c.1140 to serve the small lay community of tenants of Tortington Priory, an Augustinian house, which was situated close by. It had certainly passed into the hands of Tortington priory by 1380.

Despite its neat appearance, the S doorway must have been moved on at least three occasions. The aisle into which it opens was originally of 13thc. date, but was later removed, and the S wall moved back to its original line. The aisle was reinstated by G. C. Coote during a restoration of 1867. The chancel arch was rebuilt in 1750. The vestry was built in 1892, and further repairs were carried out in 1904 by Philip Johnson. The church was declared redundant in 1978 and came into the care of the Redundant Churches Fund, now the Churches Conservation Trust. The fragment of sculpture on the NW corner of the tower was incorporated during one of the restorations. W. F. Leeves, whose name is inscribed on the chancel arch, bought the priory estate in 1706.

Nairn and Pevsner and Peat and Halstead both give St Thomas as the current dedication.

The S doorway appears to have been carved by a different group of sculptors from the font and chancel arch, which go together stylistically. The doorway is closely related to work at Chichester and probably dates from c.1140. The font and chancel arch may be slightly later, c.1150. The only other examples of beakhead in Sussex, are New Shoreham and Arundel Castle. There is pseudo-beakhead at Albourne. This design, with alternating bird and beast beakheads facing in opposite directions, was probably copied from the cloister arcades at Reading Abbey.

The church guide book compares the font with one at Bishop's Teignton, Devon. 'PG, p.154' in GZ's index cards suggests this belongs to a group of fonts (including Honiton, South Molton and Luppitt) from a centre of manufacture in Dorset. GZ added Bishop's Teignton and Blackhawton, Devon.