Use Kindle Without Registering Credit/Debit Card?

Quote: You are not required to have a credit or debit card on your Amazon.co.uk account to make digital purchases such as Kindle books, but you must establish a default 1-Click invoice address on your account to use Amazon.co.uk Gift Certificates for digital purchases. If you don't already have a 1-Click invoice address on your account, follow the instructions below to add an address without entering a credit or debit card to your account.

To add a 1-Click Invoice Address for Gift Certificate purchases:
Visit the Manage Addresses and 1-Click Settings page in Your Account.
Click the Enter a new address button.
Enter the address information and click the Continue button.
Set the address as your default by clicking the link on the address labelled "Click here to make this your 1-Click default address." You may be prompted to associate a credit or debit card with the address, but entering one of these payment methods is not required.