I seem to have pressed a button somewhere that has screwed up several things. First, as I click verts they are accumulated as if I was ctrl-clicking them. This is annoying. Secondly, if I try to grab a model and move it about, the model stays put and the display moves. Also annoying. Thirdly and (I think) lastly, when I punch in dimensions for the model, only the mesh is resized, leaving the lights where they were and consequently FUBARing the size of the damn thing.
These problems may or may not be related. A rhubarb and custard Chupa Chup to the person who can sort my life out on this one. Place your bets!