The situation is more complicated than I originally reported.
While Recuva is reporting that it cannot read the MFT, I can launch Powerdesk and this has no difficulty telling me what is on the disk. Ir I had a corrupt MFT I would have expected Powerdesk to give problems.
Another bit of reocery software (I forget which) had no problem analysing the disk and telling me what files are recoverable. However it was only when I asked them to recover the files that I discovered that they wanted rather a lot of money from me.
In view of the fact that other software appears to run OK, might this not be a coding bug in Recova.
But I will try running CHKDSK.
