Rail services have been forced to run at reduced speeds after a train hit an obstruction on the line.

At around 7.30am, National Rail announced that the train had become damaged between Watford Junction and Milton Keynes Central.

Customer advice for Southern Rail customers said that it had struck “a large piece of wood in the Kings Langley area” and was therefore held at Watford Junction station.

National Rail added: “Southern are working with Network Rail and other train companies to establish why the windscreen of the 06.16am London Euston to Edinburgh service was damaged as it travelled through Kings Langley.

“The investigations have found that a piece of wood has been hit by the 04.57am Wolverhampton to London Euston service, operated by Avanti West Coast.

“The train which hit the piece of wood has suffered suspension damage, and is now held at Watford Junction.

“This is leading to congestion as other trains use different lines to get round it.”

Delays are expected to last until 10am and could set-back journeys by up to 45 minutes.

Some service have been cancelled. Departing from Watford Junction, the 9.13am to Tring and the 9.32am to London Euston have been cancelled for a safety inspection of the track.

The 9.43am to Tring has been cancelled because it was set to be run by the train that hit the obstruction.