Delays of up to 15 minutes possible on London Midland between London Euston and Milton Keynes Central due to signalling problem at Berkhamsted.
Trains can run through but may experience delays. Also affecting Virgin Trains and Southern.
Abellio, who run the Greater Anglia rail line, has been named Train Operator of the Year at the annual national Rail Business Awards.
Greater Anglia train operator Abellio says it's made real steps in customer service and punctuality in its first year in charge.
Greater Anglia have apologised for the delays that have disrupted services today