Described here, in The Guardian. Very similar to the WhipCar concept described here earlier, but with the backing of Stelios and his Easy brand, and Brent Hoberman of lastminute.com. Apparently it’s part of a relaunch of EasyCar, the Easy car rental service. There will be smartphone app, of course.
Interesting that someone as mainstream and conventional as Stelios is now interested in P2P. If I was WhipCar I’d be pleased; if there were never any competitors it would prove that it was a dud idea.