Passengers are being warned to travel only if necessary as trains from Milton Keynes to Watford Junction have been badly affected today.
UPDATE: Trains from Milton Keynes to Watford expected to return to normal by midday today
A fault with the signalling system at Leighton Buzzard is causing major disruption to commuters with National Rail stating that trains may be cancelled or delayed by up to 60 minutes.
Disruption is expected to last until the end of today (7/10) so people should only travel if "absolutely necessary".
People travelling between Hemel Hempstead and Milton Keynes Central have been told that these services "will be subject to major disruption and potentially very busy so allow plenty of extra time when using them".