A lot happening, not least carrying her back and forth several times from home (safe environment, but cold, and electricity expensive) to work (warm, "free" electricity, but decidedly not safe).
Suspect her early growth spurt is down to the warmth at work - 6cm with four leaves and the beginnings of two more, just a week after she was put down to germinate, is pretty rare.
Devised a safe, warmer space for her at home, inside an old fridge. I'm essentially using the LED lamp as a heater, with the insulation of the fridge keeping that heat in, and of course it's self-contained and light-tight. One of my better ideas :-)
On the down side, I think there are various bugs in the crappy old soil that I planted her in. I've seen several small flies on her already, which I've crushed.
So I moved her into a new pot with mainly fresh soil, salvaged from rotted lawn clippings, mixed with some old coco coir to let it drain more freely.
Let's see if she continues to thrive, or disappears overnight, like her most recent predecessor, eaten by lord-knows-what - at the time, I thought by a snail or slug, now I'm not so sure :-/