An article relating to this blog post on Finextra:
MPowa launches UK's Square
UK e-commerce outfit Powa has become the latest firm to launch a plastic dongle and mobile app that turns smartphones into payment card readers.
See article
Cardholder Present transactions in the UK are mandated to be Chip and PIN verified, and since this device is swipe only (like Square in the US) it would not reach the minimum requirements for such payments.
I doubt that any UK acquiring banks would issue merchant accounts for use with this device. It wouldn't be supported by Visa or Mastercard, and is against the recommendations of the Payments Council.
I fail to see how this has any legs at all. It strikes me nothing more than another media stunt by Mr Wagner.