Well, our new light arrived from Rejuvenation tonight and it is lovely. We assembled it with no problems, removed the old fixture and then had a grim reminder than we live in a 1907 house. The old knob and tube wiring is still in the ceiling, minus the insulation. At least on the visible part of the wires. It’s too dark to do further exploration, which will probably mean some plaster coming down, but tomorrow should reveal the state of affairs more.