The church was apparently destroyed by the French in 1216, and rebuilt sometime later in the C13, when the chancel, N and S arcades, N and S chancel chapels and clerestories were built.
The vaulted undercroft S of the chancel is also C13.
There was considerable work in the C14 when the aisles were widened and the chancel refenestrated.
The N porch was added in the C15.
The S vestry was renovated in the mid C16, perhaps for use as a chapel by Dutch Protestants.
In 1661 the spire and upper part of the tower collapsed, destroying the S aisle.
The upper two stages of the tower were rebuilt after its collapse in the later C17, and have round-headed lights in a classical style.
The S nave clerestory is C13 and has pairs of trefoiled lights.
The S vestry has a curved, Dutch gable of the mid C16.
The vestry undercroft, only partly below ground, is lit by two C13 openings to the N,
there are square, C16 windows in the upper parts.
There is a fine C14 E window with Decorated tracery, and the E, W, NE and NW windows of the N aisle are also Decorated in style.
The other N aisle windows are probably late C17 or C18, probably having been damaged when the tower collapsed, and have three plain lights with a central transom, all in wood, an unusual survival.
The embattled N porch is C15,
covers a C14 N door.
The W door is C19 in a Decorated style, and there are clear breaks in the masonry indicating the extent of the damage in the C17.
The N aisle is very wide, and the three-bay N nave arcade and two-bay N chancel arcade are late C13 and have two chamfered orders on polygonal piers with moulded capitals and bases.
The C13 N clerestory now opens internally.
There is an early C16 door to the treasury with a cusped, four-centred head in a square frame, the spandrels with Renaissance cherubs, in the S wall of the chancel.
The vault below the treasury is C13, and has a central pier of similar character to the C13 work in the arcades and chamfered vault ribs.
C13 three-seat sedilia in the chancel, with multi-layered, trefoiled arches on detached shafts.
Royal arms of King Charles II.
Roofs are late Medieval in character, and have tall, plain crown posts and lightweight rafters and beams, but they may be later in date due to their scantling and tall crown posts.
The principal fixtures now are monuments.
The N aisle has a series of very good late C14 tomb recesses.
There are further shields in the surround, which may have been for Thomas Ellis, sometime mayor of Sandwich, d. after 1382.
The effigies, of a man and a woman in late C14 civilian dress are very fine, and may belong to John Ellis, merchant, and his wife c.1360-90.
Also in the N aisle is a very fine, but damaged, military effigy, said to be of Sir John Grove, d.1347 although the armour is earlier, which was salvaged from the ruins of the S aisle in the late C18.
Also an unusual timber triptych with low relief foliage carving, a memorial for Herbert, d.1915 and Maurice, d.
Ledger slabs and brass indents in the floor.
A two-light C14 window with geometric tracery from the former St Thomas's Hospital was re-erected in the churchyard in 1923.
St Peter's was already a large church by the C12
wealth brought by the wool trade undoubtedly explains the size and grandeur of the C13 rebuilding of the church, which included not only the N and S aisles, but also the crypt below the SE vestry or treasury, a very unusual feature for a parish church.
There was further rebuilding in the C14, and the enlargement of the S aisle is attributed to Sir John Grove, d.1347.
The harbour at Sandwich began to silt up in the C15,
the town began to decline, although the rebuilding of the upper part of the so-called treasury in the C16 suggests a degree of continued prosperity.
The central tower at St Peter¿s was in poor condition by the mid C17, and on October 13, 1661 it collapsed onto the S aisle.
The church was patched up and the upper part of the tower rebuilt in the late C17.
SOURCES Tricker, R. St Peter's Church, Sandwich, Kent Buildings of England: North-East and East Kent , 444-5 REASONS FOR DESIGNATION The church of St Peter, Sandwich is designated at Grade I for the following principal reasons: * Large church mostly of the C13 with aisles (S demolished after collapse of central tower in C17) and vaulted undercroft to treasury. * Excellent C14 tombs. * C16 treasury with brick Dutch gable. * Unusual C17 lead cupola on tower.