Retailers are supposed to take your name and address when buying a PAYG phone/SIM with cash. I've seen a Carphone Warehouse refuse a sale because of it - althou

Retailers are supposed to take your name and address when buying a PAYG phone/SIM with cash. I've seen a Carphone Warehouse refuse a sale because of it - although they also don't verify the information you give them, so you could just lie.