Thanks Dpatt, at least for the explanation
I cannot express how p(&ed off I am with this and will NOT be buying another WD USB drive.
I bought a 3tb drive for an old PC, spent days and days transferring data to it. Then ripped it out of its enclosure and bought it with me to my new home in another country. Built a new PC (SATA 3) and plugged it in to discover this issue and then, with Google, this thread.
I don't suppose a miracle has happened and someones cracked this have they?