The tower was built in the fifteenth century and was used by the Reverend William Derham in the first accurate measurement of the speed of sound.The main monument is a large stone effigy of Sir Gabriel Poyntz (1538–1608) and his wife Etheldreda, who are lying on a marble tomb chest.Over them is a wooden tester without column supports, decorated with images of the sun, moon, clouds and stars.[3] The organ is a 2 manual Brindley & Foster instrument currently in the care of Martin M Cross builders (Grays) and on which the pitch is rather sharp at A=460.The bells are rung from the ground floor and, unusually, are hung in an anticlockwise direction.