Unable to purchase .uk domain

Domain names/DNS > Country code TLD Registration
If you're trying to buy a .uk domain name and you're getting the error saying:

Authorization error Reason:V334 Your request for domain has failed because the 'account-name' for the registrant does not fully match any registrant which has rights for this domain. 

That's because your don't own the .co.uk.  In order to buy the .uk, you must also own the .co.uk domain.