In my book “The Currency Cold War” (LPP: 2020) I mentioned the pioneering role of the world’s first digital currency system, Mondex, which was launched in Swindon in England back in 1995 (I wrote about this Silver Jubilee of the birth of new money back in July) and observed that were the system to be launched today it would be implemented using the secure element (or “trusted execution environment”, TEE) in smartphones and other devices. Well, Visa have just published a proposal to do just this. They call it the Offline Payment System (OPS) and explain that it prevents double-spending by relying on digital signatures generated by trusted execution environments (TEEs) which are already available on most computer devices, including smartphones and tablets.