A teenager died of horrific injuries after climbing on to the roof of a train moments before it sped under a bridge at 70mph, an inquest jury heard.

Student Thomas Clarke, 18, slammed into the bridge and was ripped from the roof in an act which a coroner and police said should serve as a warning to other young people not to fool about on trains.

East Sussex coroner Alan Craze said: "For society as a whole, it would be terribly worrying should our young people start getting into a culture as dangerous as climbing on top of moving trains."

Mr Clarke was in high spirits with friends when he clambered on top of the train as he headed home from last November's Lewes bonfire displays.

He ignored their pleas to come down and moments later they heard a thud as the train passed a bridge.

Elsewhere on the Connex South Central train was Mr Clarke's sister Imogen who learnt of the tragedy at the next station.

The Eastbourne inquest heard student Mr Clarke, of Woodgate Meadow, Plumpton Green, died instantly from multiple injuries.

Toxicology tests revealed he was more than three times over the drink-drive limit. He had 261mg of alcohol in 100ml of blood. The legal limit is 80mg. Traces of cannabis were also found in his body.

Dr Jane Mercer, a pathologist at the Eastbourne District General Hospital, said his perception would have been impaired and the combined effects would have contributed to the accident.

Mr Clarke's mother Teresa Epps, along with British Transport Police officers, hoped the tragedy would deter others from playing on the rail network.

She said: "I wouldn't want any other mother to go through anything like this."

Before his death, Mr Clarke, known as Tom, was looking forward to a trip to Amsterdam with Sussex Downs College, Lewes, where he was studying.

On the evening of the accident, he joined a 30-strong group of friends aged 15 to 19 at Plumpton station to go to Lewes.

Toby Hutchins, 17, of Sliders Lane, Haywards Heath, said: "We were just enjoying the night and when it came for us to go home, we were feeling a bit drunk."

Afterwards, the group made their way home on the 10.35pm train from Lewes. They were said to be in high spirits, with Mr Clarke singing but not aggressive or boisterous.

However, as the train was moving, Mr Clarke began swinging on an open door. Later, he sat with his feet through the open window and his hands on the roof.

Witnesses then saw him flip himself on to the roof despite his friends urging him not to.

He then walked towards the back of the train as it approached Cooksbridge.

Friend Tim Hayward, 16, said Mr Clarke was on the roof for about three minutes before the train passed through the bridge.

Mr Hayward, of Horsted Keynes, Haywards Heath, said: "Toby was calling him for ages but he wouldn't come back in.

"Then he got hit. We all heard a thud."

When the train stopped at the next station, panic set in as it became apparent Mr Clarke had hit the bridge.

The electricity was cut off and further trains stopped. Train driver Phil Sistrom, of Marine Drive, Bishopstone, Seaford, spoke to Mr Clarke's sister who revealed it was not the first time he had climbed on top of trains.

The jury returned a verdict of misadventure.

Outside Eastbourne Magistrates Court, Sergeant Jack Ioannou, of the British Transport Police, said: "We've heard of the tragic loss of a young life.

"Our message is that the rail network is not a safe environment and our hope is that this tragic incident will act as deterrent to other people."