Jeremy,I dug out the manual that I downloaded while waiting for my car to arrive. It is slightly different to the one that came with the car, in phraseology , here and there, but I trust the systems in the car will be the same.
The manual that came with the car is in it, outside in the cold and wet, so I will go by his one. Softy that I am.
According to it, and I hope my interpretation is correct(!) the ASC switch controls the automatic stability control and the traction control.
The default setting, ie whenever you start the car, has the ASC on and TC off.
When needing extra traction when pulling away on a slippery surface for example you would switch the ASC off which then enables the TC.
So it looks like the TC is indeed off by default which as I said before is a bit of a surprise to me but that seems to be the way it is.
If you think I am wrong please don't hesitate to say so!
The ABS must be completely separate, but in my previous cars the TC and ABS sensing was done by the same system as far as I could tell.
Blimey these manuals are not as straightforward as they could be, are they?