Note that the ANO states specifically 'ground signals' with no reference to RTF instructions, light signals. etc.
There is no method for passing the circuit direction through the standard light signals.
One will find that most aerodromes which have variable circuit directions and no signal square will only be available to aircraft with radio or at least PPR to non-radio aircraft.
However, since the radio signal passing the circuit direction is always going to come from the ground, that I believe would be a ground signal (signal from the ground).
Regards,
DFC