Thanks for info from PB Doug and yourself Jon. I take onboard the useful info about the damper axis moving through a conical plane as steering turns. What this also reveals to me though, given the damper rod movement and essence of this thread, is it's even more important to clamp against top spacers (commensurate with not compressing rubbers) to ensure the nut doesn't loosen although it is a fine 10mm thread. Clearly the bottom mount nut being at right angles to the top is not affected by this movement otherwise mine would have loosened long ago.
My steering has always been very light but given Jon's findings I'm hoping the application of rubber grease will allow the rubbers above and below shock mount plate to turn whilst clamped down onto their spacers. If not I will cut and fit some slightly longer spacers from suitable tubing.
Having accepted that there is a conical movement by the damper rod, If the top of the damper is clamped hard down to the damper plate, nothing there can move and it suggests to me that the rubbers will have absolutely no effect at all. The whole conical movement forces will be transmitted directly to the damper plate; there is no give. Consequently, something will have to give or deform, such as the damper rod itself, as PB has said.
As for some nuts undoing, think they are nylocks and as such should always be renewed after removal. Even a spot of loctite may help but for me, I am firmly sticking with what I have always done.
Looks like we have to agree to differ on this one.