I don't usually carry any cash with me (my wallet has nowhere to keep coins). People are reluctant to give out their bank account details to receive money. If the recipient needs to be sure that they've been paid then they'd have to login to online banking - not very convenient.
I keep getting told that sending money using PayPal is free. It's only free if you allow them to take money by Direct Debit from your bank account, at which point all payments then default to using this payment method (instead of a Debit/Credit Card). So for the ability to make ad-hoc free payments I then have to be careful to change the payment method on every other transaction - not very convenient.
Paym appears to solve both of these problems. As long as the recipient has registered to use Paym, anyone can send money to the mobile number of the recipient. The bank account details of both sides remain private. For confirmation that money has been paid, a text message is sent to the recipient at the time the transaction occurs stating the sender, reference and amount.
In my testing (which requires two mobile numbers) the Faster Payment transaction took 7 seconds to complete and the text message arrived 1 second later:
The minimum transaction amount is £1 and the limit per day is £250.