The plan of the church below shows it in the later years before the Reformation with the positions of the features of the church and the use of the various spaces. The text below describes the inside of the church.
The features inside the church at Harby in the later years of the middle ages, before the split from Rome in the Reformation, were much the same as in other village churches.
The Harby font, as is shown by its style, is from the Decorated period. It probably stood in pre-reformation times as was the custom of that time by the main entrance, the south door. This symbolized the entering of the individual to the church through baptism. The inscription 1606 inscribed onto it later may be from the time when it was moved in post-Reformation times.
The walls were decorated with scriptural scenes and possibly a last judgement. Eight coats of arms were seen and described in 1622 but only one remained in 1790, located in the “upper end of the north aisle”. The notes on the Victorian restoration say they found evidence of wall painting on the west wall of the nave. “In cleaning all of tower in the church there had clearly been colouring, red and blue, of fresco but it came off with the mortar and plaster so that it was impossible to make it out. They however were figures.”
A Rood screen which held a large sculpture of Christ on the Rood or Cross stretched across the church between the nave and chancel.
The windows had stained glass.
Statues of the Saints, including St Mary the patron saint of Harby were common. There would have been a statue of St Mary in the niche now empty half way up the west wall of the tower.
Round the walls of the church were probably the stations of the cross.
At the east end of the chancel there was the aumbry on the north and a piscina on the south wall.
There was an altar at the east end of the south aisle with a piscina on the south wall nearby.