Commuters are facing delays on London Overground services between Euston and Watford Junction this afternoon.
An operating incident at Stonebridge Park and a points failure at Harrow & Wealdstone is causing disruption to journeys between London Euston and Watford Junction, National Rail said.
The train operator said London Overground services may be delayed by up to 30 minutes or cancelled.
National Rail said the disruption was expected to continue until 4:30pm, then a few minutes later revised that estimate to 5.15pm. The disruption is now expected to continue until 7.15pm.