Now that the 8.1 upgrade is available which apparently is more desktop friendly, I decided to re-install Windows 8 and then obtain the upgrade to Windows 8.1
During the install procedure for Windows 8 it asks for the product code and when \I entered my code it refused to accept it.
Eventually getting through to a (semi) human at Microsoft I explained the problem and was told that, having downgraded (their words not mine) from Windows 8 to Windows 7, I had sacrificed my Windows 8 licence and would have to purchase a new one.
As I said... there's a thing