Trains are unable to stop at Arlesey due to a blocked line.
A train with a fault is currently (February 28) blocking one of the lines between Hitchin and St Neots - meaning services travelling towards Peterborough are unable to stop at Arlesey.
However, trains travelling towards London are unaffected.
If you need to get to Arlesey from Hitchin, Thameslink is advising you to travel to Biggleswade, and travel back to Arlesey.
If you are at Arlesey, and need to travel towards St Neots, change to platform 1, and take a Hitchin bound train to then travel back towards St Neots.
DIsruption is expected to continue until 6pm.