Thanks Marc, great info indeed.
But, I was under the impression that the audio control switch is on the RIGHT handside of the steering wheel on the UK models and if there was cruise control switch, it would be on the left side of the steering wheel. You seem to have marked the left side of the steering wheel in the UK pic
I have exactly the same shape steering wheel by the way. (I changed my steering wheel to a 2005 model leather one)
EDIT: I just got the answer to my question
It seems that the 2005 xtrail in the UK scored the cruise control as an additional feature. This resulted in the audio control switch being moved to the LEFT side of the steering wheel (as shown in your photo) and the cruise control switch to be located on the right side of the steering.
It is all starting to make sense now and I think the difference in part numbers is actually (left & right)
I can buy either one, because both slots on my steering wheel are empty (I have an aftermarket cruise control)
I still would like to hear from the guys in the UK about the RIGHT mounted audio switch if possible and also to know what exactly it controls (apart from volume up/down)