I have just noticed whilst browsing round the admin settings, that the PayPal Subscription facility was set to TEST MODE and the currency was US Dollars! D'oh!!
This meant that no money was ever taken from users and users were not able to sign up via the subscription method.
Those that have tried to sign up as PayPal Subscription, I have checked our PayPal account and no money has been received and therefore I have cancelled the pending invoice and set you as Registered Non Members.
I'm very sorry for the inconvenience.
Pete