We had an expert mathematician calculate from charts at what time the sun would be at it's highest point in the sky at 4.2 degrees west of the Greenwich Meridian. He told us that would happen at 13.19 - and that's exactly what time it was when the shadow fell across the notch!
Can I ask...did the mathematician work this out prior to and separately from your timings and the two results compared afterwards or did he give you a time and you worked from this? Also did you film this event...I'd like to see footage of it...not for critique or analysis but just out of curiosity.
He's eighty-odd years old and thinks we must be mad because the quoit is probably just a random old pile of rocks! lol
I had previously taken photos and the time was recorded in the RAW file metadata. My colleague asked the old man to calculate when the Sun would be at it's zenith for 4.2 degrees west of the meridian but without knowing at what time I had photographed it. We later returned and took another sequence - Result shadow on notch at 13.19 - QED!
We're planning on recording video footage in the near future (just waiting for broadcast quality cameras to be delivered!)