Security outfit McAfee - trying to generate some PR around the importance of users appropriately securing mobile devices - has put in a UK Freedom of Information request to come up with the fact that in 2013 more than 15,000 mobile phones were handed in as lost property on London’s public transport (trains and buses). Shock, horror, think of the implications if they weren’t carefully secured.

Sorry to be an old skeptic, it’s my job.

Yes, 15,000 is usually thought of as a large number when dimensioning something. Usually.

But is it a large number in the context of smartphone-owning Londoners and tourists? Millions of them. Travelling every day for a year? My rough calculation is that 15,000 hand-ins comes to around 40 per day, which actually seems rather low. Perhaps what we’re really measuring here is the sad propensity of people NOT to hand in lost property?

The number of much more desirable tablets handed in might give the game away. Sure enough, just 506 tablets were handed in over this year - way less than two a day. You decide.

But whatever’s going on with the numbers there’s no doubt that securing your screen or gadget against unwanted attention when you leave it for a few minutes or a few hours is an ongoing tussle. It’s not an open or shut case though (sorry about that). It’s about finding that illusive sweet spot between turning the security off because of the pain of constantly having to password or PIN the screeen back again, and having it set at an interval that flicks it off because you really have gone to loo. I think scientists have finally discovered that such a sweet spot doesn’t actually exist.

Which is why Google is chasing password-free authentication for Chrome OS, although clearly the technique would work for all sorts of devices and systems. The idea is that your proximity and the fact that you’re probably wearing or holding a smartphone, ID badge, bluetoothy watch or Google Glasses - something that, by its own proximity, can validate its owner to a sister device via Bluetooth or NFC - should be enough to do the trick.

Does this approach have holes? Of course it does, but such a system would give better protection than a disabled alternative.