Ok, long story.
Golf laid up in storage for a few years after it's extensive/expensive resto. Golf travelled to the US in 2013.
Now you know the sound with ignition at position 1 with the fuel pumps whirring. It sounded a bit weak when I collected it. Also, idling was a problem. 400 miles home, and the car is fine.
A few months later, the whir is sounding weaker than ever, until one day, no whir, and no starting.
So - bets please - what died?