Thousands of passengers were delayed this morning as a power failure halted trains travelling from Clapham Junction into Victoria station. (And there'll still be delays on the commute home as a result.)
There were 1,000 unlucky commuters stuck on one train for five hours who were eventually rescued by London Fire Brigade with the help of Network Rail and British Transport Police.
The train was just 200 yards away from a gate into Wandsworth Common according to one commuter stuck on the train, while police took supplies of water to the stranded passengers.
But why couldn’t they just disembark?
Here’s how the morning unfolded - and why some passengers had one of the worst commutes of their life. (Here's the science bit.)
Trains in the south east have a mysterious sounding third rail. It’s not really that mysterious. While the rest of the trains running into London are powered by overhead electric cables, Southern trains are powered by an electrified third rail which each train is connected to... when they're running.
This third conductor rail was damaged this morning, causing the trains running over them to become damaged.
All the trains running on the route had to be stopped, several of them between stations with the knock-on effect that all subsequent scheduled trains were delayed.
Each damaged train - network rail doesn't have an exact number but said it was in single digit figures- then had to be moved either on to the next station or the one it had just come from.
Logistical nightmare anyone? A time-consuming task with each train, and its passengers, waiting their turn to move.
Every stranded train was able to be cleared this way - except two. One had to be hauled to a station with the help of a diesel engine locomotive. It’s thought that particular train had left Brighton at 6.56am and wasn’t able to reach a station until 12pm.
The other could not be moved at all, and those even more unlucky commuters were faced with even more setbacks.
After managing to move the other trains, they had to wait for the power to be switched off. It’s extremely dangerous for anyone to be on the tracks when the power is still running on the track.
What about the emergency services attending the trapped passengers, I hear you ask?
Even police are not allowed on the track without permission from Network Rail and its staff there to oversee things.
Even then, it’s still dangerous.
Network Rail say similar situations have caused some passengers to force open doors on to the track to escape.
But they thanked passengers affected today for being patient and understanding. Not all passengers will be pleased with that though.