Nigel,
Are you using a TRS stereo cable INTO that box? Tha'ts what gives it the power ... as long as the box is plugged in, or course.
Yes, I definately am Dave. Still it doesn't draw power from the box, just runs the battery flat. And the light on the box is orange rather than green. I suspect there may be a problem with the box because I had expected it would power the guitar.