Following a 30 mile drive parked the car and on return would not start.
All Ign lights worked etc but no starter motor or solenoid'click'.
Problem turned out to be that the immobiliser module in the Ign key had dropped out and so far not been found.
Using spare key all back to normal.
Moral - don't panic ask the dealers advice (Phil at A&W pointed me to this as a possible solution.
The module is the small 2/3mm dia black 'pimple' on front edge of plastic section of the key and is approx 20mm long. Make sure yours is firmly stuck in
If this had happened away from home even Recovery Companies would not have been able to help.