Aha, mystery solved. Thank you kind sir.
Otherwise, things are going quite well for me in Lightroom. One thing that strikes me is that it seems a shame that they did not make the spot removal tool into a proper clone tool while they were at it - it is almost there, except that you cannot move the tool across the image. After all, you can use a clone tool for spot removal, but not the other way around. So often one needs to remove an unruly twig from the edge of the frame.
John