An unbuttressed C13 tower in coursed rubble with quoins, of 3 stages with moulded plinth and 2 string courses.
The west face has a C15 2 light window with a rectangular niche over which pierces the string course.
In the 3rd stage on all faces except the east are C13 double belfry lights with colonettes and blank trefoils in the tympana.
The tower has a C14 broach spire with 3 tiers of lucarnes, the lower two in the compass directions, the top in the diagonals.
To north west corner of the nave long and short Anglo Saxon quoins are exposed.
The north door is C15 with a square hood mould and is flanked to the west by a C15 2 light window
to the east by a pair of C14 2 light windows.
The east aisle window is a C14 light with curvilinear tracery having hood mould with human mask stops.
The north clerestorey has a plain parapet with a lead roof behind drained by 2 grotesque gargoyles.
The 2 windows are C15 with 2 lights under shallow 4 centre heads with hood moulds.
At the north east corner of the nave further Anglo Saxon quoins are exposed.
The north side has a C17 2 light cross mullioned window with ogee heads under a square shallow hood mould.
The south side has 2 string courses between which is found a C12 round headed single light.
The south chapel has a shallow lead roof behind a raised gable on the east side which is lit by a C14 2 light window.
The north aisle has a splayed base and plain moulded parapet concealing a lead roof which is drained by 2 gargoyles.
There are 2 large C15 3 light windows east of the porch and a small niche or light to the west.
The C15 south door has a niche over it and an inscription recording the porch's construction in 1486.
the 3 bay south arcade of C13 double chamfered arches has keeled responds which would originally have been flanked by 2 smaller piers,
a circular eastern pier and a replacement octagonal western pier on which an inscription reads "ista columna facta fuit ad festum Sancta Michaelis Anno Damini MCCCLXXX at nomen factoris Thomas Bate de Corby" translated "This column was made for the feast of St. Michael in the year of our Lord 1380 and the name of the maker was Thomas Bate of Corby".
The C12 3 bay north arcade has circular piers, square abacii and nicked corners and heavily scalloped capitals and round arches with one step, one chamfer and a half roll.
The bridge is decorated with carved faces, 2 being very small.
Carvings in a pillar on the south aisle
The tower arch is a recut C13 opening, the chancel arch is C13 and matches the south arcade.
The nave roof is C15 and braced with human mask corbels.
The chancel has a C14 aumbry on its north wall and a C14 double niche or sedilia on its south side.
The south chapel is early C13 with one bay of triple responds and a double chamfered round arch.
It has a C14 piscina and aumbry.
The pews are C19 although some retain C15 poppy head bench ends.
The pulpit is C20.
In the east window of the north aisle are remnants of medieval glass and a small fragment of an inscription "de Welby".
An engraving by Fowler dated 1809 shows this window before it was damaged and it is clear that it referred to Sir John Welby of 1376.
The porch was built by Bishop Richard Fox, founder of Corpus Christi College, Oxford, who was born in Ropsley in 1447/8.
Sources: H.M. Taylor and Joan Taylor: Anglo Saxon Architecture Treasure beyond Measure: Lincolnshire Churches Trust p.83.