A derailed train between Milton Keynes Central and Watford Junction means there is major disruption to services between Milton Keynes Central and London Euston, affecting both London Midland, Southern and Virgin Trains.
Two of the lines have reopened at reduced speed through the affected area but journeys are expected to be delayed by up to 60 minutes, revised or cancelled.
Disruption is expected to continue until the end of the day. For more information, click here.