BRIDOL is the British Sundial Society's Register of Fixed and Mass Dials, which gives detail and photographs of about 8000 fixed sundials and 3000 mass dials in the UK.
Some of these are in private gardens, but the majority are publicly available.
This dial is really very unusual, there are only a few others in the country. For obvious reasons it is called a cross dial, but technically speaking it is a version of a Polar Dial. On a normal horizontal dial, as in your garden, or a vertical dial on the church wall, the shadow moves circlewise around the face of the dial over the day. On a polar dial the shadow is a straight line which moves across the face of dial over the day. On the horizontal, or vertical dial, the gnomon is aligned to point to the pole star around which the earth appears to rotate, but it is the dial face of the polar dial that has the polar alignment. I hope that explanation is helpful, but more can be found in this British Sundial Society website.
The two edges of the top of the cross will cast their shadow onto the top of the arms, and the edges of the side arms cast shadows on the vertical part. You will have to look closely to see the hours marked.
A Jewish version of this dial is in the shape of a Star of David.
