The Natural Philosopher wrote:

..because I have yet to meet a dimmer switch that applies any live to
the electronics when actually switched OFF.

But this is a pull-cord dimmer. I've no idea how those work, but maybe
there's no hard-switched off state? That being the case a suitably
mounted 33 or 47 k ohm 2 watt resistor across the output (SW-L to N)
might do the trick.

--
Andy