Longcase clocks with 1¼ seconds pendulums are particularly rare. The first longcase pendulums were short, for the verge escapement. As this required a wide arc of swing it was not practical to apply a longer pendulum as the case width restricted the arc of swing. But it was appreciated before the invention of the anchor (1669/70) that a longer pendulum would produce more accurate timekeeping. For a short time afterwards there was some experimentation with the length of pendulums for this new escapement. The 1¼ seconds pendulum has the advantage of reducing timekeeping error, owing to its slower swing and smaller arc. However, it has a tendency to rock the case, sometimes causing the movement to stop altogether. The present clock's escapement has been changed for a seconds pendulum but remarkably the original plinth lenticle for the longer pendulum and 1¼ seconds subsidiary ring remain.