Passengers could face some difficult journeys to work over the next few months after a delay in delivering new electric trains.

The number of services on the London Overground route between Watford Junction and London Euston was scheduled to increase from three an hour to four, from May 19.

But Transport for London says this cannot happen because staff training and delivery of trains still needs to be completed.

Although TfL is not ready, it has to stick to a new timetable which has been agreed by all rail companies which share the same line.

It means three trains will run an hour still, but there will now be a 30 minute wait between the the last train of the hour and the first train of the following hour (updated).

Services will be temporarily retimed from the current 20 minute intervals to 15, 15, and 30 minute intervals.

Trains will run at approximately 15, 28 and 44 minutes past the hour from Euston and 16, 29 and 46 minutes past the hour from Watford.

Once the new trains are delivered, four services will run during the hour.

The new electric trains will also be brought onto the line to increase capacity and offer USB charging points, free Wi-Fi and improved real-time passenger information screens on board.

TfL is unsure at this stage when the new trains will be ready.

Stations including Watford High Street, Bushey, Carpenders Park, Hatch End, Headstone Lane, Harrow & Wealdstone, and Kenton, will all be affected by the temporary changes.

Customers are advised to check before they travel, particularly before May 19, as the times of their services will change.