The warranty would be with Apple. In UK, the consumer rights put an obligation on the retailer to sell you goods fit for purpose and free of defect etc. for a minimum of 12months, the 'guarantee'. Therefore most buyers in UK don't need to bother with the manufacture's warranty. However, the retailer only has an obligation for items it's sold you, normally bound with proof of purchase.
I don't know the answer, but I bought my iPhone 4 while on assignment in Asia, dropped it on return to the U.S., took it to a U.S. Apple store and they replaced it for free, without ever asking where I bought it. I don't have AppleCare, either, and I told them the truth about the phone having fallen.