Much rebuilt by 1657, including the W tower, after a fire in 1645.
The dominant features are the W tower and the N transept which are from the two key building campaigns, in the mid 17th century and 1828-9 respectively, both quite unusual dates in English church-building.
The S aisle was much rebuilt in the 17th century: it has no parapets.
its three large pointed windows have three-light Perpendicular tracery and were designed by Hayward: a fourth window to the E is small and has grid-like mullions and a transom which looks like a simple 17th-century design yet is not shown on a pre-1820s picture of the church.
The inner doorway on the N has 14th-century moulding and is perhaps reused.
The nave and aisles are of five bays and the arcades are probably medieval survivals.
Also from the 1840s is the font , a very richly treated piece in Beer stone and similar to the font installed by Medley at St Andrew's, Exwick: it is octagonal and has ornate ogee arches on the bowl and much crocketing, quatrefoil work and an inscription round the top.
The royal arms at the W end date from 1682.
The pulpit (c1903) is a traceried wooden piece and stands on a marble base: it probably dates from the 1870s restoration.
The church has many wall monuments.
The largest is to Sir Thomas Northmore with a circular inscription flanked by two columns: it has two standing allegorical figures and two more (winged) reclining on a broken pediment.
The church was burnt in 1645 in the Civil War and much rebuilt by 1657.
Mid-17th-century and 1820s work on the scale of St Thomas¿s is quite unusual in English churches and thus this gives the building special importance.
The 17th-century work was altered in the 19th century but the tower is essentially intact and is an important example of Gothic survival into the post-Reformation period.
Howard Colvin, A Biographical Dictionary of British Architects, 1600-1840, 1995, p 741.
Antonia Brodie et al., Directory of British Architects 1834-1900, 2001, pp 874-5.
REASONS FOR DESIGNATION: The church of St Thomas the Apostle, Cowick Street, Exeter, is designated at Grade I for the following principal reasons: * It is of outstanding interest as a church of medieval origins which was remodelled in a series of important campaigns in the 17th and 19th centuries. * The 17th-century work is an important example of Gothic survival, using the architecture of the Middle Ages in the post-Civil War rebuilding campaign. * The 1820s work at the E end is unusually lavish for its time.
It is generously scaled and gives the building an imposing E end. * The refitting - reredos, altar, font and seating - in the early 1840s is a pioneering example of its kind. * Of older fittings, the lectern is of great importance as the earliest surviving cathedral lectern in the country.
There is also a series of wall monuments, two of which have considerable distinction.