Well, I got there at last. Her Royal Highness will now go around 6ft curves without derailing or shorting.

I did have to introduce some springing to restrict the movement of the bogie.

There are two spring wires at the rear which fit between the inner and outer bogie frames. They restrict the sideways movement of the rear of the bogie. The bogie pivot point has side control springs which allow more movement at the front of the bogie. This sort of worked but the front of the bogie was so light that it had a tendency to lift of the track so I added a second element of springing which holds down the front of the bogie and all runs nicely. This spring has a loop which is held in place by the pivot screw then bends over the front of the plate that you can see in the image below before curving onto the front of the bogie frame. Although it looks huge in the enlarged image it’s only 0.5mm spring wire.