There was probably a small Norman church at St Merryn, but what you see now is the result of the changes made in 1422 when the Dean of Exeter extended the chancel and the parishioners responded by having the south aisle built with pillars of Cataclews stone and gothic arches separating it from the nave. The wagon roof dates from this period and some of the roof bosses are original. There is a fine font (similar in style to that at St Petroc's, Padstow) dating to about 1450, also of Cataclews stone. The royal coat of arms of Charles II which is positioned in the north-west corner is a plaster relief dating from 1662.