A failed signal caused chaos for thousands of rail commuters this morning, including those using Thameslink services.
A spokesman said most northbound services from Brighton were running "reasonably normally" but were terminating at Luton instead of Bedford.
The signal failure, between Flitwick and Bedford, mainly affected passengers on southbound services from Bedford. It also hit those using Midland Mainline routes.
A Thameslink spokesman said: "We understand a main cable has failed and that it happened around 6.45am.
"This is one of the worst mornings we've had. We have laid on buses, but there is not enough room on them to cope with all the passengers. We are advising people not to travel unless necessary."
He added: "We are tearing our hair out over all this and no doubt the passengers are too."
Bus services were laid on to help passengers continue their journeys south to London.
Some passengers decided to abandon any attempts to make it in to work. One said: "I'm giving up and going home. It would have been lunchtime at least before I would have got to the office."
A spokeswoman for Network Rail said the problem was probably caused by a cable fault.
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