Ok, well that was the danger of making predictions!
Having got my hands on one at Warley, and persuaded the owner to let me borrow it Saturday night, I took it apart in the hotel room, and surprise, its on 3mm diameter axles running it very neat brass bearings. Wonder if this means Bachmann have returned to 3mm diameter as their future standard.
Also discovered the leading and trailing wheels pick up as well as all four driving wheels. One wheel of each of the radial axles is live to its axle, one side at the front and t'other side at the rear, and passes the current to the main pick up strips in the keeper plate....a very neat arrangement. Oh, and if you decide to remove the keeper plate....beware.....the radial truck springs can fly out!
Many thanks to Bob Blood for allowing me to discover this!