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around 7uA, still enough to give a tingle!
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Not sure I can feel 7μA as a tingle. To get a response on such low currents, I stroke the conductor with the back of the fingers, which causes a muscular response that can be perceived by the resulting vibration, instead of feeling the current itself.
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If the primary winding was powered by a floating earth free supply, then would that stop any capacitance induced voltage [referenced to earth] in the secondary winding ?
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No, unfortunately. The problem as mentioned above is not just that the secondary is coupled to the primary, but that it is always coupled to earth by its stray capacitance whatever form it takes. Even a hand-cranked AC generator that has no electrical input, will have stray capacitance and hence be able to produce earth leakage despite perfect insulation.
The question is, what is an acceptable leakage current for something that is considered to be electrically separated from earth? It depends what you are trying to do with it. For example, 200μA is quite harmless, much lower than the limit for touch-leakage on Class II appliances, but will still light an indicator. Imposing a leakage limit in turn imposes a limt for the stray capacitance (or its unbalance) which imposes a limit on size. The bigger your transformer, the higher the capacitance so the higher the leakage is likely to be.