After installing some bearings under the main spring and removing the damper blades I expected the shimmy to go, but it's still there.
Put your damper blades back on. The steering bearings decouple the main springs from the stub axle, but they won't stop shimmy caused by the steering angle being too steep.
So that would suggest Tim that all post damper blade models with R & P steering will suffer from shimmy, which is clearly not the case. I can't see anything in later Morgan front suspension/steering evolution that would allow shimmy unless rack/kingpin/bush/bearing wear, tyre problem or some adjustable, including ride height not optimised.
As Simon suggests having track rods horizontal at static ride height is best compromise.
