Not satisfied with being home to the wizardly Platform 9 3/4, King's Cross station is also home to the distinctly non-magical platform 0.
This glitch in the matrix only appeared in May 2010, when the platform was officially opened by then Transport Secretary Philip Hammond as part of the complete refurbishment of the station. Before the refurbishment, the platform didn't exist, and the numbered platforms started at 1.
The new platform was added underneath the new Network Rail offices, next to the existing platform 1. With platforms 1-11 already in existence, it didn't make sense to name it platform 12, as it would be the opposite side to the station from platform 11. Renumbering all of the platforms was ruled out, to avoid confusing commuters who used the station regularly and were familiar with the existing layout.
There was talk about naming it platform Y (it's on the side of the station running parallel to York Way), but it was thought that having both letter and numbered naming systems would be confusing to passengers — let's face it, it's a chaotic enough station already.
A couple more facts about platform 0: it's the longest platform in the station, as it was designed for longer trains, to increase capacity on the network. Furthermore, diesel trains are not allowed to use this platform except in emergencies. The reason for this is to reduce pollution affecting York Way residents, and to prevent fumes from entering the station's ventilation system.
As we reported in our secrets of the trams video, West Croydon station has no platform 2.