This whining just started in mid-journey yesterday. The volume of the whine varies but it's noisier when accelerating up hills or when travelling at speed and lifting one's foot off. However, it can also easily be heard when stationary and in neutral, when a quick press on the accelerator - say up to 3000 revs - and then foot off, produces a clearly diminishing whine. In days gone by, I recollect failing clutches used to whine but this one performs when vehicle is not in gear & not moving!

Might it be the turbo charger packing in?

Any thoughts would be much appreciated.

My 1.9tdi did that before randomly going into limp mode. It sounded a bit like a siren in the distance most of the time but would get noticeably louder.(bit like a blow off valve)before going into limp mode. Turbo actuator was sticking causing I think overboost. Had P0234 fault code. I sprayed it with wd40/penetrating oil and manually operated it for a good while until it freed off. Been fine since then although I did put a couple of bottles of wynns turbo cleaner through the car in case the turbo was carboned up. If your turbo is like mine and variable vane then it could also be that the vanes are carboned up.

Alasdair