OK, after several tranquillizers and much grey hair, I found out why SQL Server 2012 will NOT install on Windows 8.1 Professional. 

The issue lies with the fact that SQL Server requires the .NET Framework 3.5 ,which is NOT installed by default.

OK you say, download it from the Microsoft website and install it ...dahhhh.

Gotcha!!

It will download HOWEVER it will not install NOR can you switch it on via the program / windows components. 

 Don't believe me try it. A KNOWN FEATURE from the Microsoft website.

The plot thickens now !!!

What you must do is to bring up the command prompt AS AN ADMINISTRATOR and type in the following command. The SQL Server 2012 media must be in the DVD drive.

DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:d:\sources\sxs 

Here is the URL for the reference article is

http://msdn.microsoft.com/en-us/library/hh506443(v=vs.110).aspx

Happy installations and the best for the festive season.

regards Steve Simon