Sundial to rear of Glynllifon House

The sundial located at the rear of Glynllifon House is a large structure made of cast iron. It features a gnomon that is supported by a 4-meter high Ionic column, which is similar to those that support the pentice in the kitchen courtyard. The gnomon rises diagonally from the ground and measures approximately 7 meters in length, extending in a northerly direction. At the base of the sundial, there is a circular timber dial faced in tinplate, where the degrees were originally marked, although these markings have now faded. It is likely that there was also a designated area of ground for taking readings, but this area has since become overgrown.

A stone plaque is fixed to the back wall of the house, near the conservatory, which provides important information for interpreting the sundial. The plaque is inscribed with the following message: "Correction - To find Greenwich Mean Time add to the hours and minutes indicated by the sun-dial the number of minutes corresponding to the day of the month below for longitude 4 .18. west," followed by a table of figures.