23% of people booking practical driving tests in the UK do so on a mobile device

"Meanwhile, up in Nottingham, the Driving Standards Agency has just redesigned its practical driving test booking service.
[...]
Results? Over 23% of those booking and 27% of those changing practical driving test bookings are now doing so from a mobile device. (Overnight it hits nearly 60% – hypotheses welcome!)
Booking your driving test is not a trivial process. Users  have to choose a date, a venue and give contact details and the like. Yet give people a decent mobile-optimised experience, and they’ll lap it up on their smartphones or tablets."

Source:  Blog post by Tom Loosemore of the Government Digital Service, 12th March 2013

Note - It takes a long time to book a test:

Old driving test service booking time = 15 mins. New version = 10m34s = 4m26s saved per user x 9,666 users yesterday = 714 user hours saved.
— John Ploughman (@johnploughman) March 12, 2013