St Matthew’s Harwell exemplifies the architecture from Traditional Norman, through early English, to decorated. It appears to have been constructed as follows: 1190-1200 North and South Transepts, 1200-1220 Tower and Nave Arcades, 1270-1310 Chancel, 1275-1325 South and North Aisle Walls and reconstructed Porch, 1975 Ground Floor and Upper Room extension to North Wall.