Yep, that was it. I figured there was some kind of "hard switch" but couldn't find it for the longest time. But there it is, right on the front.
What's the rationale for having both the hard switch AND the soft (Fn-F8) switch, other than confusing people? Thanks for your help.
You're welcome!
Well, the reason for the 'hard' switch is that it enables an easy switch-off of the wireless radio device, in places where the presence of such devices may be a hazard- like inside aeroplanes and near critical life-support medical equipment. Although the software switch suffices, it is more safe with an easy-to-access hardware switch, which anyone can get hold of, to switch off the device.
The software 'switch' requires the prior knowledge of using the laptop, and this is dangerous when the person who uses the device has left it unattended, and switched on, in a sensitive area.