Northern Scotland seems to have a curse when 'most areas' (if I may use that phrase :) ) are having a fine spell or fine summer.
It was interesting to see the hourly sunshine for places like Heathrow, Odiham and Charlwood for mid afternoon. I was in Sussex / Surrey borderlands then and the Ci thickened up, culminating in patches of Ac. The sunshine became very weak at times though there were usually some slight shadows. It also seemed to become quite a bit cooler after about 3pm. The loss of recorded sunshine by the KZ sensors seemed reasonable, though perhaps less 'bright sunshine' than shown - different Campbell Stokes estimates might have varied quite a bit this afternoon.
As a rather bizarre PS, while driving through the Hindhead tunnel on the A3, the car thermometer read 29C at entry, and 24C on exit, about a mile later (1.14 miles to be exact, according to Wikipedia). Some response lag so had we been going even slower in the BH weekend traffic, it probably would have dropped more. By chance the car therm. seems to be accurate, unlike previous car where it depended on whether or not you were driving into the sun. The tricky thing is to find out where the sensor is.