Okay this is starting to get there......
Firstly thanks to Dartho if I use the code he kindly provided in .htaccess then one of my alternative true domains (
www.tekguru.co.uk) does indeed remap correctly on top of the main site and retains the original URL.
1) First of all I do not own the mobile.4winmobile.com domain, no need to acording to ServInt as this is a valid subdomain of
www.4winmobile.com. According to them the correct way of setting it up is as a subdomain.
Are they wrong here?
If I delete mobile.4winmobile.com as a sub domain I can ......
Try to park mobile.4winmobile.com on
www.4winmobile.com. I fI try this I get an error.....
Argh I don't believe it - 5 times it blinking errors, I try it now and it parks! Argh!!!!
And the Mod has kicked in as well and is working.
God knows what the problem was!
Cheers for the advise guys

Very happy now!