From their post:
Terms are simple: Buy 3, get a 4th Free - for every four items you order, the cheapest is free. Postage as normal.
Offer applies to everything EXCEPT minis - we don't hold enough stock of them to discount them at present.
Sale discount applies ONLY to orders mailed directly to us at firstname.lastname@example.org.
Sale starts today and runs through 'till midnight 31st January. Loyalty Card credit cannot be used to buy sale items.