LMB:
The Works S is classed as a seperate car, not modified. If you phone up MINI insurance they have it down as the 'Works S', similarly they have the 'cooper works' as well. I think the information was only released a day or so ago.
I've not tried any other insurance companies yet, but I'm sure the info will trickle down to the other ones.
Now all I've got to do is phone round and get the car insured
Cheers
Michael