Could you enlighten me the business model of Three UK?
http://www.three.co.uk/Store/Pay_As_You_Go_Price_Plans
The 321 plan offer you 1 GB of data for 10 quid, no time limit.
http://store.three.co.uk/view/searchSimOnly?tariff=3003
On the other hand you can purchase a the same 1 GB data for 10.49 and it will be valid for a month only. What's the deal?
Please also consider this:
http://www.prepaidgsm.net/forum/showthread.php?t=8477