Well, I've now put in more little lights in the ceiling - they are arranged in a cross shape, with alternating blue and white lights (I found that just white bleached out too much of the blue tones I like, and too much blue was just too overpowering)  So there's blues set to 3 and the whites set to 1 - all with ranged fall off.

And the strongest light is the blue one in the orb set to... set to... um 30 or 50 I think, I can't check - the darned thing is rendering and although it was quite fast to begin with it's slowed down a great deal on Antialiasing the Orb's support...

It took ages reducing all those lights down to where the scene wasn't bleached out, at one point I even tried playing with a big negative light outside, as all the ground out through the arch went weird. but all's well now. 

The scene is a little darker than I'd planned originally but that does show up the electric haze around the orb very nicely.

I'll post it as soon as it's finished, provided the galleries are working at the time.

Thanks to all for your help, and I hope you like the result...

Measure your mind's height
by the shade it casts.
Robert Browning (Paracelsus)

Fran's Freestuff

http://franontheedge.blogspot.com/

http://www.FranOnTheEdge.com