Next time you head out of London's Waterloo station keep your eyes peeled as you come through the ticket barriers; if you're lucky you'll see one of the small display screens that are usually covered by an opaque lid. At first sight these seem to be a mirror of the larger departure boards on the main concourse but these screens tell the drivers which platform they need to be on for their train before the main concourse screens update.

Why is this interesting? Well, tonight the trains in and out of Waterloo were severely disrupted by something going on at Clapham Junction, no one seemed to know what exactly but the general consensus amongst the station staff was that it was probably related to a train.

Train departures were still displayed on the main board with a platform number, but after it became apparent that the service wasn't going anywhere, each departure cycled through on time, delayed and finally cancelled.

After my train home suffered this fate I trudged to the end of the platform where a member of the SouthWest Trains was looking at one of these driver's display screens and was actually dispensing useful information. Admittedly the information seemed to be "catch the Tube if you can" but that was still useful.