I would bet all the generators will be offsite and well hidden to save the embarrassment of the UK not having charging. For some reason, Jaguar have not made much effort to install chargers and many buyers have been refunded after not being able to drive very far then get trailered to a charger.
Tesla supply a diesel generator to fit on the tow hook for long journeys. It runs during the journey to keep it topped up.
London taxis have a small engine under the bonnet to re-charge when parked up.