Old Wardour Castle is one of only a hand-full of medieval castles that are built to a geometrical plan. The main body of the castle is hexagonal in shape and has a hexagonal courtyard at its centre. To the front of the castle is a rectangular block with two tall towers. Other castles with a regular geometrical plan include Bodiam and Nunney, but Old Wardour is unique in its design. Even the curtain wall of the castle is partially hexagonal.
Aerial photographs of the castle seemed to show that the orientation of the front of the castle was to the north-east. There are two large windows on the front of the castle that provide light to a large hall probably used for banquets and entertaining. This alignment to the north-east seemed strange as more light could be obtained by aligning the castle to the south. Their alignment to the north-east would only have let in direct sunlight at the sun's extreme range - the Summer Solstice.
Referring back to the diagram of Old Wardour's location relative to Stonehenge it appeared that the alignment of the castle was pointing up the line to Stonehenge.
A comparison of the alignments, shows that the alignment of Old Wardour Castle is slightly to the south compared to Stonehenge. It has been difficult to obtain an accurate measurement of this angle as I have three plans and all disagree. Two compass readings taken at the walls indicated values of roughly 57 and 60 degrees. Currently magnetic variation is 2 degrees west of north. Observations of the afternoon sun when approximately in line with the axis indicated a bearing of 236 degrees.
So, the angle of Old Wardour castle is shown on plans in this discussion as 57.5 degrees purely as a guide.
Stonehenge is aligned to the Summer Solstice on June 21st, the longest day in the northern hemisphere at approximately 50 degrees. This is when the sun is furthest north.
Below is a more detailed plan of the castle showing it's alignment, shape and relationship to the curtain wall.
But why is there a slight difference in angle of the axis?
Directly in front of the castle is a hill. Thus, there is likely to be a delay of some twenty or thirty minutes before the sun appears over the top of the hill and it striking the face of the castle. Could this be the reason that the castle is angled slightly to the south in comparison with Stonehenge?