Not my field, so I'll take your word for it, but are you able to explain
*why* a lower rated tube will pull more line current ? Just curious.



Because to get the lower wattage they changed the gas fill, this causes
the arc voltage to be reduced, but at the same time the current is
increased. The net result is that wattage is reduced, but only because
the voltage is reduced further than it would be if the current stayed
the same.

If I recall right, you're in the UK which uses choke ballasts, reducing
lamp voltage on those increases current to a greater degree than doing
so with HX (leak) autotransformer ballasts so the wattage would stay the
same or even rise.