EXTERIOR: The exterior is wholly of the later C15.
The ground floor has a shallow tierceron star vault with intermediate ribs carried by demi-angels holding shields with the arms of the see of Lincoln.
INTERIOR: The interior is of a consistent late C15 design, but weather courses from an earlier church, which had much lower and more steeply pitched roofs, survive internally on the E, N and S faces of the tower.
Low box pews in the nave have the ends, doors and fronts decorated with richly carved, Early Decorated-style trefoiled arches.
The choir stalls, reading desk and pulpit have Perpendicular style blind tracery and carved figures.
The unusual chancel tiles in geometric patterns, which have bands of fine brass tracery panels inset in areas more prone to wear, are contemporary.
Delicate early C20 screen with figures including St George under the tower arch.
Some medieval furnishings survive.
A re-cut medieval stone altar slab is re-used in the C19 high altar.
There are C15 piscinas in both the chancel and the S chapel, with a further recess, possibly a former sedilia in the chancel.
A small amount of C15 painting in a damask pattern survives on the chancel arch.
The S aisle roof is C15 and has a moulded ridge and principals.
There are several medieval doors, including those to the tower and porch vices and to the chamber over the porch.
Royal arms of 1758, over-painted in 1808.
There are five windows of fine late C15 glass, reset in 1759-60 by the noted glazier Peckitt of York.
That in the E window may be partly original to St Martin's, but most of the glass was removed from Tattershall church in 1757 and given to the Earl of Exeter.
There is a very fine group of monuments to the Cecil family, Lords Burghley and later Earls of Exeter, of nearby Burghley house in the N (Burghley) chapel.
The latter is among the most imposing of all Elizabethan funerary monuments, as befits Burghley's historical stature. and John Cecil, fifth Earl of Exeter and Anne (Cavendish) his wife, dated 1704, a neo-classical statuary group by Pierre-Étienne Monnot, a French sculptor working in Rome who also designed statuary for Burghley House: this is one of the finest tombs of its day in the country, displaying strong antique tendencies as befits its Roman creation.
There are also a number of good C18 and C19 wall tablets including a provincial tablet to the Dutch portrait William Wissing d. 1687
there is also an unusual ceramic panel in the N wall to Thomas Goodrich d. 1885, 'a rare cricketer', some C18 and early C19 floor slabs, and a group of C19 hatchments.
HISTORY: St Martin's may have been among the buildings damaged in the sack of Stamford by the Lancastrian forces in 1461, as it was said to be ruinous in 1473.
Rebuilding was started in 1482, and completed in 1485.
The glass also has heraldry for Russell, Rotherham and Chedworth as well as Richard Fleming, Bishop of Lincoln 1421-31.
SOURCES: RCHME Stamford , 18-23 Pevsner, N and Harris, J., Buildings of England: Lincolnshire , 691-3 REASONS FOR DESIGNATION: The church of St Martin, Stamford is designated at Grade I for the following principal reasons: * Church with outstanding fabric of the late C15, in a unified design. * Fine C15 glass from Tattershall church, moved to St Martin's in the mid C18
re-set in typically C18 geometric patterns by Peckitt of York. * Excellent monuments of the C16-C19, especially those of the Cecil family in the Burghley chapel, of high artistic and historical importance. * Excellent and very complete mid C19 fittings designed by local architect Edward Browning and paid for by the Marquess of Exeter.