The chancel was rebuilt in about 1250 and the south door with its narrow pointed arch and the lower part of the north wall survive from this period.
The windows were replaced about 1330 in the decorated style.
The outer arches of the side windows have the same roll moulding as the east window (1330) and about 1480 the earlier side windows were replaced by the present ones in the Perpendicular style using the existing openings. (The east window was not changed)
The four bay arched braced roof dates from 1480.
On the south wall are monuments to John and Mary Darby. John Darby (d1639) left £100 towards rebuilding the tower, established charities for repairing the roads and causeways, but most important of all gave £10 to found a Free School to educate the poor children in Latin and English.
Bedingfield memorial - the large coloured monument on the north wall, is for Anthony Bedingfield (d, 1652) - a London Merchant. He purchased the two manors in 1649 for £4000.
Restored c1860 by the second Revd. Thomas Colyer. Wooden reredos - with slates painted with signs of the Evangelists and a central text; the Commandments, painted on sheets of zinc; decorative tiles on the floor of the sanctuary.
The elaborate niches on each side of the chancel are for, on the south side, Revd. Thomas Colyer, Rector 1797 - 1859 and of his wife (d. 1847) and on the north side, their son Revd. Thomas Colyer, rector 1871 - 1890 who restored the chancel c1860.
In the 1480's widened by nearly four feet. The widened nave is one of the widest and longest aisle-less naves in Suffolk. The chancel arch was rebuilt to centre on new width of nave.
The earlier 14th century north doorway and the tower arch were retained. The hood-moulds, over the south door and the recess in the south wall, are similar, showing they are part of the new work. The north door, which remained in its earlier settings, has no internal hood-moulds.
South doorway - as there was no porch on the south side, the doorway has deep internal recesses for a wooden beam to secure the door.
Four large windows were built on the new south wall. The window openings on the north wall were widened to accommodate three new windows.
The roof - the mortices at the end of each of the hammers and the shorter wall posts show that they once had horizontal figures attached. Four, now headless, figures remain at the east end, as a canopy of honour over the Rood. At the higher level are a pair of praying figures - at the lower level they hold a shield and a bible.
The Rood screen - Before the Reformation the east end of the nave had a carved and painted wooden screen across its full width with side panels to north and south. On top of the screen was a loft or wide balcony, above which was the Rood - the figure of Jesus on the cross flanked by St Mary and St John. Access to the loft was by a staircase often built in the thickness of the wall - which may account for the rubble wall to the right of the chancel arch. The lower part of the screen was probably removed in the Victorian restoration. Four panels from the screen are displayed in the chancel - traces of original red, blue and green colours can be seen.
Side altars - Either side of the chancel arch was an altar - one to St Mary and the other to St John the Baptist. The base of a former altar and some medieval floor tiles survive on the north side.
Font - 15th century. Believed to be the work of Hawes of Occold. The eight sides of the bowl have carved panels with symbols associated with various saints - lilies for St. Mary, an eagle for St. John, an angle holding a shield with the arms of St. Edmund, a lion for St. Mark, a surpliced angel with a shield on which is the symbol of the Trinity, the angel of St. Matthew, a feathered angel with a shield depicting three calices and hosts and the ox for St. Luke.
The font cover is 17th century, the sides of which are decorated with scrolls and bird's heads. Hidden under the cover, on the lip of the font, are the remains of the medieval locking bar, to prevent the water being stolen
Wall paintings - To the right of the south door are a pair of overlapping, incised and painted consecration crosses, showing where the church was blessed, after the widening look place in the 1480's. During restoration work in 1928, four blocks of 17th century text were uncovered, two of which are still visible today. Over the south door were the Commandments; in the recess, fragments of letters; to the right of the chancel arch, another set of Commandments; and east of the pulpit, Proverbs Ch. 8 vv 32 - 36.
Glass - The north east window contains some 15th century glass and examples of the earliest botanical depictions of English wild flowers in the country - there are fourteen blue ones are columbine (aquilegia vulgaris). It also includes a headless figure of St. Catherine and a variety of feet and faces
Benches - seventeen 15th century poppy headed benches are to the west of the font, with a further ten incorporated into the later box pews (numbers 6 - 13 and 16). The benches inside pews 2, 10 and in front of 16, have figures on the arms.
Pulpit - in a typical 17th century position. The lower two sections are earlier then the pulpit which dates from 1802. The Parish Clerk sat in the bottom desk, from which he led the responses and amens. The clergyman conducted the service and read the lessons from the higher reading desk. There was an hour glass in the frame.
Box Pews - constructed in 1810 - originally 19 pews of which 15 remain, numbered 2 - 16. The Squire's pew for the Lord of Gislingham and Swatshall was No. 1. This stood where the organ now stands. It was removed in 1933 to provide a site for the new organ. In the 1991 restoration pews 17 - 19 were removed to balance the seating on each side. This is when the medieval floor tiles were discovered
Hat pegs - 19th century
Gallery - erected before 1770. Used by musicians and singers.
Organ - 1870 Bevington and was originally in All Saints, Dickleburgh - installed here in 2001.
Royal Arms - The arms of George III date from 1806.
War memorial - The boards on the wall at the north-west corner of the nave were originally in the Methodist Chapel that was in Mill Street and were brought here after it closed. It is fairly unique in that two of the panels record the names of those who served in the First World War.
Repair to mullions - check out the far window on the south. The stone mullion has been repaired with oak! When? We don't know but it must have been before Diocesan Advisory Committee and English Heritage!
The north door is 17th century.
The first tower was under construction in 1386 and was 80 feet high. It collapsed in Feb 1599. In May 1638 the wardens appeared before the Commissary's Court at Lambeth, where they were ordered to proceed with the rebuilding, to raise funds and to cleanse the churchyard of the rubbish.
The tower was built in 1639 using 200,000 bricks fired at Allwood Green. The tower is 60 feet high and 12 feet square on the inside. The walls of the ground floor are five feet thick. The material from the old tower was used to make the churchyard wall and also using some of the surplus bricks from the ‘new' tower.
Bells - The four medieval bells recorded here in 1553, survived the fall and were placed in a temporary cage. In 1640 they were recast into five bells by Miles Gray of Colchester. Three of these turned out to be defective and were recast by Miles Gray and Michael Darby in 1641. The other two bells must have developed faults as they were recast by John Darby of Ipswich in 1671. A sixth was added in 1814. By about 1920 the frame had deteriorated to such an extent that full-circle ringing was prohibited and the bells were chime rung only. In 1966 the frame was declared unsafe and beyond repair and the bells were lowered to the intermediate floor. In January 2005 an appeal was launched to raise £91,000 to fully restore the bells (two of which had developed large cracks and had to be welded). Two additional new bells were cast by Whitechapel Foundry. A new cast iron frame was installed below the old oak frame and the bells hung. They were rung for the first time in December 2006. It was made possible through a number of personal donations and grants including £41,000 from The Heritage Lottery Fund.
Bell ringers - Inside the tower are decorative panels with the names of the bell ringers of 1717. Below the panels are the initials of their successors.
Peal board - There is one peal board (there have only been three peals rung). It records a record ring on 6th April 1822 of 10,080 changes of Grandsire Bob in six hours and 35 minutes. The names of the ringers are given and around the edge are their bells and their trades - bricklayer, two blacksmiths, sexton, turf cutter and shoe maker.
Built after the alterations to the nave in the 1480's. An inscription over the door is in Latin ‘Pray for the souls of Robert Chapman and Rose his wife, who caused this porch to be built to the honour of God'