Phew!

[lostcarpark]

Just about managed to get my computer back in order. The old hard disk seems to be back from the brink, and all the data has been transferred to the new one just in case. After I got the OS on the new drive, I put the old drive in and booted up (ignoring the message that the drive needs repairing). There was an extra drive there, but no data was visible. Not encouraging. Rebooted, and let the full drive repair take place (which took about an hour). Find data is back on drive. Copy data to new drive. Breathe sigh of relief.