Soon after setting off this morning I heard two strange noises from the area of the real left speaker. Initially I dismissed them as stones or a stick in the wheel arch. Soon after a smell of burning was noticed. Stopped the car.
No obvious exterior problems, but strong smell inside and clearly vivible whisps of smoke coming from the back left speaker. smoke and smell dissipated after a short while. No further problems noted and even the speaker appears to work fine.
For what it's worth there is a big thick bundle of wires routing through that area - More than necessary for the speaker alone.
Therehad been a little light rain overnight, but not much.