The Flying Scotsman's trip through Watford this evening happened ahead of schedule following an unrelated incident on the railway line.

Trainspotters were set to catch a glimpse of the iconic locomotive passing through the town today (May 18).

The world famous locomotive has been making its way down the West Coast railway line ahead of tours which start up again later this week.

The steam engine embarked on its journey from Carnforth in Lancashire at 10.10am today and has made its way down south, through the Midlands, and around 5pm, would have been passing through Northamptonshire.

The Flying Scotsman had been scheduled to pass through Watford at around 7.20pm, but at around 5.30pm, railway companies began reporting that emergency services were in attendance at an incident between Milton Keynes and Watford.

There has been confirmation from rail companies that a person has been hit by a train.

National Rail says all lines are blocked and there are reports of a heavy emergency presence at Hemel Hempstead station this evening.

The Flying Scotsman had been scheduled to pass through Hemel shortly after 7pm.

Although all lines are blocked and disruption is expected until the end of the day, a real-time train timetable has suggested the Flying Scotsman's journey was pushed ahead of schedule and passed through Hemel at 6.45pm and through Watford at 7pm, with the train now in north west London.

The schedule up until 6pm today had been for the Flying Scotsman to pass through 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

The Flying Scotsman's final destination tonight will be Southall in west London, before tours from London Victoria start Thursday.

The vintage steam locomotive was built in 1923 and it now does special passenger tours of the UK.

The locomotive is currently owned by the National Railway Museum and it was retired from regular service in 1963.