Okay, I have managed to get a solution for my particular problem.
The symptoms:
1) New AppleID (the transition from MrStrathmore to my primary email address) worked fine on iPhone. Could access previous purchases and password was accepted for App store.
2) Could view account settings vias Settings - Store on the iPhone with my password.
3) Could not login to iTunes store on Win7 PC
4) iCloud in iPhone settings was on permanent 'Verifying' status and email never arrived.
5) If I tried to check my AppleID existed on appleid.apple.com by typing in my name and email, the site said I did not exist.
6) I could login to 'Manage' on AppleID site but site said a verification email had been sent (which never arrived) and atempts to resend it never appeared.
7) If I tried to reset my password via email option, it never arrived.
8) If I tried to reset my password via security question it said my date of birth was wrong. (Also, in the account setings on my iPhone, only my date and month were shown.... no year.)
The way I have cleared the error was as follows;
1) Go to appleid.apple.com
2) Clicked 'Manage' account and entered new email AppleID and password
3) On the screen that said verification had been sent, clicked edit for the AppleID and Primary email address.
4) Entered a single word (my old AppleID name) and tried to change.
5) Got error as not a valid email
6) Re-entered my new AppleID (email)
7) Saved changes and requested a new verification email. This appeared in seconds.
I can now login to iTunes and when I went to iCloud settings on my iPhone, the verify completed and everything now works.
What a complete mess. I guess the Apple systems were stuck in some sort of dead-end with my account. If you have a similar set of symptoms, give it a try. Especially if you are waiting for a verification email......