Well finally decided to take the time and upgrade my W8.1 to Windows 10
The thing I find interesting, is the Machine (HP Compaq 8510p) I purchased new with XP PRO originally installed at point of sale years ago.
The machine was updated to W8 Pro after many years of excellent XP service. The machine was then updated to W8.1 Pro where it now sits ready and "capable" of running W10 Pro.
Interesting

Addition: Process took 58 minutes
Only one program needed reinstalling (MS Network Monitor) Others updated and Reset to W10 once OS rebooted.
Very Smooth.