Thanks very much for the message and the pictures.
We were soon warm once we got the heater going in the van but speaking for myself I was very tired and slept very well last night.
We did both enjoy our day enormously thank you. I am sure, just as I hoped, that Jon got a lot out of it and as you remarked he seemed to get the hang of the technique pretty well. We were so lucky with the weather too and the river looked in good ply. There is obviously a good grayling population on those stretches.