Update: car has lost the infotainment screen and driver information screen as in both are blank. Transmission selection is still visible. Rang VW dealer whose advice was to leave it for an hour, ie 'switch it off and on again'. Tried this, no change. Rang emergency VW breakdown number which actually calls the AA. As promised AA van arrived within the hour. AA guy sat in the car, held the infotainment on/off button down for 10/15 seconds and, hey presto!, all back to normal.
Most peculiar! Going to get it checked by VW!