A double points failure at Berkhamsted is causing delay and disruption to train services in and out of London. 

The first fault, which occurred at around 8am, was repaired by engineers within an hour, but the points failed again soon afterwards. 

As of 12pm, Network Rail is carrying out further repair work but this has led to two of the four train lines being shut. 

The remaining slow lines to and from London are heavily congested, with an extra ten trains per hour to accommodate in each direction.

London Midland and Southern trains are subject to cancellation or severe delay until further notice. For the latest information, check the Berkhamsted station departures board.