This picture, taken by passenger Martin Stewart, shows the broken cable hanging over the track in Radlett station yesterday.
Severe delays have been predicted on Southeastern, East Midlands Trains and First Capital Connect until the end of the week.
More top news
The man believed to have murdered Alice Gross walked into Britain unchecked despite having a conviction in Lativia for murdering his wife.
Former residents of the Chagos Islands have lost their latest legal challenge at the Supreme Court.
Their warning depends on whether negotiations for a post-Brexit Britain do not offer freedom of movement for people, capital and goods.