Hi Johnt,
No, Kings College don't aggregate the results into a single index, they just compare each test with the previous results, and can see speed of progression, or improvement!! They have measurements of non PWP to compare with, such as the volunteer assistants in their twenties. One of these students said to me, "You have a faster reaction time to me". I told him, "Great, but you can walk and I can't!!" Another interesting test they have just included is photographing my face, splitting the photo down the middle, and joining two left hand sides and two right hand sides to make a complete face to see if there is any difference in the left or right sides.
You can read about the group on
http://www.whatsdrivingparkinsons.net/index.html
Ron