A person has been hit by a train this evening.

Southern Rail says the incident has happened between Watford Junction and Milton Keynes and that all lines are blocked. 

Police covering Dacorum posted on Facebook that they were supporting British Transport colleagues at Hemel Hempstead station.

Southern Rail tweeted at 5.25pm: "It is with great sadness that we report a person has been hit by a train between Watford Junction and Milton Keynes.

"All lines are blocked between these stations whilst the emergency services work to deal with this incident. Service information will follow."

National Rail added: "The emergency services are dealing with an incident between Watford Junction and Milton Keynes Central. So they can safely do their work, all lines are currently closed. Trains may be cancelled or diverted until the end of the day."

National Rail has since updated to say that some lines have reopened, however trains will still be cancelled or delayed by up to 60 minutes until 9pm.

The incident in Hemel Hempstead happened around an hour-and-a-half before the Flying Scotsman was scheduled to pass through Hemel and then Watford.

It has transpired that in light of the incident in Hemel, the Flying Scotsman's journey was pushed ahead of schedule and passed through Hemel at 6.45pm and Watford at 7pm - 20 minutes earlier than planned.

This is according to a real-time train timetable.

There were doubts the famous locomotive would even be able to travel through Hertfordshire due to the lines being blocked, but it appears the train has been able to pass through.

According to a real-time train timetable, the locomotive was scheduled to be spotted at the following stations or junctions at the following times today.

Hemel Hempstead - 7.11pm

Apsley - 7.14pm

Kings Langley - 7.18pm

Watford North Junction - 7.23pm

Watford Junction - 7.24pm

Bushey - 7.26pm

Watford Observer: The Flying Scotsman. Credit: Getty ImagesThe Flying Scotsman. Credit: Getty Images

National Rail says usual services on the West Coast line like Avanti West Coast, London Northwestern Railway, and Southern are affected by this emergency incident.

Tickets are being accepted on alternative routes including via London St Pancras and Overground and Underground lines.

Rail replacement buses have been requested.