Welwyn Garden City train station. Picture: Charlotte McLaughlin. (Image: Archant)
Trains are unable to run towards Finsbury Park from Stevenage via Welwyn Garden City due to a broken down train between Knebworth and Welwyn North.
Trees that are overhanging on the track are also to blame for train delays from Finsbury Park to Hertford North.
This may result in cancellations, delays or revisions for Stevenage and Cuffley-bound passengers on Govia-operated Great Northern services.
Network Rail engineers have had to turn the power off in order to remove the trees from the line at Winchmore Hill.
This means that trains are currently unable to run up to Hertford North from Moorgate.
Delays are expected until 8pm.
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