All lines have been reopened after two incidents on the railway were dealt with - but passengers are warned to still expect delays to their journeys.
Commuters have been facing delays and cancellations since midday between London Euston and Watford Junction.
There was a broken down freight train near Harrow & Wealdstone and a points failure near Watford Junction.
At 2.20pm, National Rail said both of these issues have now been cleared.
The London Northwestern Railway line has been struggling between London Euston and Milton Keynes.
Therefore, services via Watford Junction, Kings Langley, Bushey, and other stations in between, were disrupted.
National Rail tweeted at 2.25pm that journeys may still be disrupted by up to 45 minutes and added that some services may still be cancelled.
London Overground services have not been affected.
Passengers are advised to check before they travel.
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