Train passengers heading for London Euston warned to only travel if necessary on Wednesday
Rail passengers heading to London have been told to travel only if absolutely necessary on Wednesday.
Train operators fear the disruption will last all day limiting services to two trains an hour in each direction leading to services being busier than usual.
London Northwestern, Avanti West Coast and Southern services between Milton Keynes and Watford Junction are all affected.
A National Rail spokesman said: "A power failure in the Leighton Buzzard area has caused damage to the signals in both directions around this station.
"Network Rail staff are on-site working to fix the issue but estimates from site means this work will take a large number of hours until being complete.
"Network Rail have implemented an emergency special working plan to allow some trains to run through the area."
Check the National Rail Enquries journey planner HERE to check if your train is running.
London Northwestern say they have ordered road transport to support the limited services at Milton Keynes and Northampton and passengers can use tickets on East Midlands Railway and Thameslink Midland Main Line services or on Chiltern Railways.
LNR's services between Northampton and Birmingham are not affected.