Apparently this is for amazon customers only and you have to register through the ordering process with vistaprint. This includes 500 business cards with a matt finish and a design on one side only.
You have to go to: http://www.vistaprint.co.uk/savings3
which takes you directly to a screen that lets you design your own personal business card.
After you design it, click through select 500 for £5.00 and click through the next few screens, make sure that you read everything on the screen thoroughly as about 6-7 pages are designed to make you sign up for extra stuff and add extra costs.
BUT make sure you click on the free metal case. Eventually you get to the final screen which add on VAT and delivery is free.
There are other deals at http://www.vistaprint.co.uk/savings7
but do not have free delivery
BUT you can only get one deal at a time or it will charge you full price for one of the items.
It is a little complicated but it does work, please do not expire it early as I have warned it is a little complicated to get the deal