NOW I know what the difference is in appearance - one is s blue file and the other is a round FireFox coloured logo that stands up and says "here I am". I took DrByte's advice and asked my Host to have a look at the index.php issue in case it was an Apache thing. They have since come back and said "index.html takes priority over index.php
You have a blank index.html file in your /public_html directory." .... made sense so I have spent 20 minutes or so looking for the blank index.html file - found about 15 or so files in different folders and none of them are blank so I have asked the Host to specify exactly where the offender is situated so I can add the content to it that appears in every other example, i.e.
I have by the way deleted the index.html file from the root and it made no difference so I reinstated it. That file was in the root when I made a FULL site back up prior to installing 'Dual Pricing - Wholesale Pricing' plug-in which stalled with the forbidden access issue with Install SQL patches in admin/tools, which is now all sorted after the host whitelisted the appropriate files in mod_security.
So now I am awaiting a response from the Host - for the life of me I cannot figure in which folder the offending file is - every obvious folder in admin and includes has been thoroughly searched as have other folders like Auto Loaders.
Hopefully this gets sorted soon and I can get back to business development rather than putting out spot fires :)
cheers and Many Thanks for your assistance to date.