A rail worker who almost caused a major disaster when he threw a metal bench on the track has been jailed for 18 months.

More than 150 passengers had to be led to safety after their train ploughed into the bench on the main London-Brighton line and came screeching to a halt.

Former British Rail worker Martin Keane, 57, dashed to the scene to help - and stole the driver's jacket and wallet containing £20.

Sentencing Keane, Judge David Stokes QC said: "You knew it was inevitable it would cause damage to the train and endanger the safety of the passengers."

Keane, who had worked in track maintenance, was arrested on the platform at South Croydon station, yards from where the terrifying incident took place on March 17 last year.

Peter Warne, prosecuting, told how the Connex South Central Victoria to Littlehampton service was travelling at 50mph when its driver spotted the bench.

He said: "The driver was unable to stop given the weight, speed and number of passengers on the train.

"It struck the bench which Keane had placed on the track some moments before and was caught by the station's spy cameras.

"Happily no one was injured but investigators say the train may have derailed."

All passengers were evacuated from the halted train, causing massive delays on the busy line.

Keane, who was sacked in 1995 for drink problems, managed to obtain a key to the cabin. He unlocked the door and stole the driver's jacket containing £20.

When police arrested drunken Keane moments later he said he had 'no memory' of placing the bench on the track.

Gordon Ross, defending, said: "I can offer no explanation for his actions.

"It may be suggested it was a revenge attack, but he was fired some years ago and he even speaks highly of his employers."

Keane, of Tanfield Road, Croydon, admitted theft and endangering passenger safety.

He was sentenced to 18 months' jail, including three months for absconding from trial last year.