I have now had a health check of the battery which indicated 85% efficiency however there was only a 45 % charge. This after the battery had been charged to full capacity by the dealer 2 days previously and the car subsequently operated at speeds of up to 70 mph. for around 1 hour.
The loss of charge is unacceptable and the dealer indicated that the alternator was operating correctly.
Is it still the battery or the voltage regulator?