Thank you LVR and your indi, I think you may have fixed my problem. I removed the right hand side Vanos solenoids (consistent with error on cylinder 1) and flushed them out using carby cleaner. Until I took them out I didn't realise there was a fine mesh screen on them which would be very easy to block. The solenoids looked clean enough but apparently they were not. There may be a slight hesitation on heavy acceleration (I can't remember what it was like originally) but there is no sign of a warning light and the car is quite drivable (at last!).