The church features architecture by Edward Doran Webb and stained glass by Charles Eamer Kempe. The Forster Chapel, a lady chapel added to the south face in the 13th century, contains the alabaster effigial monument of Sir George Forster and his wife Elizabeth which was built in 1530. Evidence suggests that the chapel may originally have been a chantry dedicated to St Nicholas. The roundel windows in the north wall date from the 13th century and are the oldest glass in Berkshire.