London's sprawling Overground is slowly taking over the capital. The Overground's tentacles are slowly enveloping more and more of London's suburban rail services, to the point where eventually the map is going to look like someone has scrawled all over it with an orange marker.
But even the rather overbearing map doesn't tell the full story, it turns out.
Blogger Lee Butterley has recently posted about an intriguing "secret" Overground route - one that only comes into action whenever there is engineering on another part of the network.
During normal services, trains regularly travel between Willesden Junction and Stratford via Hampstead Heath and Gospel Oak. But when engineering work hits that part of the network, TfL secretly operate services between Willesden Junction and Stratford, but via Queen's Park and South Hampstead instead. If that doesn't seem weird to you, take a look at the map - which makes the journey look impossible.
Huh? As Lee goes on to explain in his post, it's all made possible by a normally abandoned stretch of track that links South Hampstead with Camden Road. There must be a few baffled faces when the train from Stratford to Willesden Junction pulls into not Kentish Town West, but South Hampstead.
If you'd like to travel on this "secret" route yourself, you can do so this coming weekend, as the appropriate section of track is closed - meaning that (in theory) this secret route should be in operation. And do be sure to read Lee's full blog post on the secret line, as it contains more fascinating details. [UtterLee]