BBC
Multiple signal failures were causing “major disruption” on trains between London and Luton, National Rail said.
Operator East Midlands Railway said the issue was preventing it from running services in and out of St Pancras.
A Thameslink train calling at London Luton Airport was delayed by nearly two hours, putting air passengers’ journeys at risk.
National Rail warned cancellations and severe delays were expected until the end of Wednesday.
It said the fault was related to work over Christmas to install a new system to control signals on the line.
Route director Gary Walsh said: “I am very sorry that our engineering work is affecting passengers today.
“There is a fault with part of the signaling control system which means we need to reduce the number of trains which are able to run.”
Thameslink said: “Please do not attempt travel between Bedford and London Bridge until further notice.
“The earlier disruption caused by multiple signal failures has now reoccurred.
“Due to the level of disruption, passengers are advised to delay travelling until later. National Rail posted advice to passengers and alternative travel options on its website.
It said: “A fault with the signaling system between St Albans and London St Pancras International means that trains…
