The NHS is warning of a worst-case scenario over Christmas as an "unprecedented wave of super flu" drives infections across the country.   An average of 2,660 patients were in hospital a day with flu last week - the highest ever for this time of year and up 55% on the week before.   There is no peak in sight - so what's caused the predominant H3N2 strain to emerge and can the NHS cope with the extra pressure?   Niall is joined by NHS GP and health educator Dr Raj Arora and Sky's science correspondent Thomas Moore.   Producer: Tom Gillespie  Editor: Mike Bovill