The second lesson was to avoid stopping on long steep hills on hot days; without the cooling generated by movement of the wheel, the heat in the motor would seep into the electronics and trigger a No-Start situation. Solution incidentally, is to freewheel a few yards down hill to allow it to cool down!
For those interested in more detail, here's the brief blog that I kept along the way.
https://davidggalloway.wordpress.com/bilbao-to-uk-on-an-e-trike/