OK

Just rang Blaupunkt (finding their number on the net) and they tell me that cannot connect an ipod to ah astra stereo system.

So I rang Holden Customer Assistance and they tell me that there are standard RCA Jacks in the back of the stereo system. "All I need to do is" take the unit out and connect a cable - one end 3.5mm plug for the ipod/2 x rca plugs. Exactly how easy I suspected it to be!

Looks like a visit to Holden dealer - they told me it couldnt be done (were they just being lazy - I can't believe noone else has done this before me).