Lib Dem peer, Lord Carlile, the government's reviewer of anti-terror laws, broadly welcomed the phone tap idea but warned the government not to see it as a "silver bullet".

BBC: A phone tapping device

Why carry cards and cash when you can swipe your phone or tap it to pay for goods and services?

FORBES: How would you like to pay? Smartphone

Whereas with Mastercard or American Express the consumer just presents their card and signs, Visa users had to hand over their phone numbers and tap in security details on their own phones.

BBC: iZettle and the modernisation of money