AN investigation has been launched into another failure of overhead lines near London Paddington.

The incident stranded a number of trains, which were evacuated, but not before British Transport Police had issued an appeal urging passengers not to attempt to leave their trains without qualified assistance from staff.

Services to Heathrow Airport were particularly affected by the incident, around midday yesterday, and frustrated Heathrow Express passengers tweeted that they would miss their flights.

It was the second failure of overhead lines between Paddington and Hayes in less than two weeks, but sources said this failure was not the same as the first. In the earlier incident, an Hitachi Class 802 bi mode train under test brought down 500m of wire near Hanwell, reportedly because of a pantograph fault.

The cause of the new failure is not yet known.