This is more of a "note to self" should I have this issue again.
When I first designeed the site I tested the user registration system and it worked just fine but this was before I added the K2 content manager and also before the latest version of reCaptcha. Up until now I really have had no need for user logins but now I have some special donor features available for downloading files upon donations I needed to implement a user management system for downloads and this is where I discovered the user registration system was busted.
The issue was that I updated to the new "1 click - i'm not a robot" Captcha protection which is evident on contact forms and throughout the site but when I visited the registration page the old captcha element was displayed and I had no idea why this was. The issue was that when I entered in the result it would always fail with either "empty result" or "wrong text"
After hours or testing and googling I finally tracked down the issue to be the fact K2 was enabled to allow user registrations and within K2 there is a separate captcha setup. All that was needed was to simply disable the use of the K2 captcha which then allowed the global captcha to be used.
The joys of managing a friggin website!