It's back, finally. The laptop went off to the insurer's preferred fixer and came back ten days later (with a new screen, shiny!) only to frustrate me for 24 hours of attempting to reload all the things I had taken off it. It said it was attached to my wireless network, but was taking about ten minutes to access a webpage. And I made several attempts to get Migration Manager working to transfer between imac and macair.
I resisted booting equipment around the room. I mean kicking. I rebooted quite a lot.
In the end I phoned the insurer who agreed I could take the laptop to the place I had wanted to take it to in the first place - Western Computer near Temple Meads in Bristol. There, they diagnosed that whoever had fitted the new screen had damaged one of the two aerials, so it needed a new screen. And now I have my laptop back and it's working. Migration Manager took about three hours but everything seems to be there, and I have no excuse for not writing. Apart from the fact that I am meant to be tidying up for Xmas visitors.