Stuart, here are the two screenshots… time taken was seconds after it shot up to 100%.
Note the time on computer clock.
John
OK well as expected this falls into the category of YYGT (Yes You Get That) 
Seriously though a reading of 5 and a max of 3 and you get greater than 100%. This happens to most folks whether or not they have the solar sensor shaded or not. The design of a Davis solar sensor is one which measures global solar not direct, that is it reads the whole sky including any reflections etc. This makes life difficult when you are estimating the sunshine as a % from actual w/m
Stuart, thank you for your time, trouble, and advice. I have followed your suggestions to the letter, using your suggested settings, and I have modified my lat/lon as per Google Earth.
Thanks again!
John
No problem. Don’t forget to check the lat/long on the solar control panel as well.
Stuart
Wilco!!! 