Zeebrugge ferry disaster: What caused one of the UK's worst maritime tragedies?

This article is part of Yahoo's 'On This Day' series

It is 35 years since one of the UK’s worst peacetime maritime disasters.

On 6 March 1987, 193 people were killed when the Herald of Free Enterprise car ferry capsized shortly after leaving the Belgian port of Zeebrugge bound for Dover.

The roll-on roll-off ferry became unstable after it set off without its bow doors being closed, allowing the sea to flood its decks.

Vehicles rolled around inside the ferry as water poured in and it capsized within the space of 90 seconds on to its port side on a sandbank.

Read more: Memorial service marks anniversary of Zeebrugge ferry disaster

There was no time to send an SOS signal or lower lifeboats or hand out life jackets.

Watch: Zeebrugge families remember victims of ferry disaster

The only escape route for many was to smash windows and climb on to the side of the ship.

The tragedy unfolded just before 6.30pm after the eight-deck car and passenger ferry left Zeebrugge with a crew of 80 and 459 passengers on board, many of them readers of The Sun, who had used the newspaper’s promotion of a reduced price trip to mainland Europe.

Rescue helicopters were dispatched and aided by the Belgian Navy, which was performing an exercise in the area at the time.

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Both the UK’s Royal Navy and Belgian Navy divers rescued people from the vessel.

Most of the victims died from hypothermia after being trapped inside the ship in extremely cold water.

Gillian Lashbrooke survived the disaster, along with two of her stepbrothers, but her mother Eileen, stepfather Keith and uncle David died. She was just 16 at the time, and jumped into the sea to survive, before being rescued by a fishing boat.

In 2017, on the 30th anniversary of the tragedy, she told the BBC how she identified her parents in a makeshift mortuary in a gym.

“I couldn't believe I was looking at my mum,” she said. “I loved her so much and she was dead in front of me.

"She wasn't just my mum, she was my best friend. The night before, she'd given me some money just before I went on deck and said, ‘Get something to eat love, and I'll see you in a minute'.

"That minute never came. That was the last time I saw her."

A public court of inquiry into the disaster placed the blame on three of the ferry’s staff: assistant boatswain Mark Stanley, who failed to close the bow doors after falling asleep in his cabin during a short break; first officer Leslie Sabel, who failed to ensure the bow doors were closed; and captain David Lewry for leaving port without knowing whether the bow doors were closed.

The company that owned the ferry, Townsend Thoresen, was criticised for its “staggering complacency”.

Mr Justice Sheen, the judge who presided over the inquiry, said poor communication was the root cause of the capsizing, identifying a “disease of sloppiness” throughout the firm’s hierarchy.

An inquest into the tragedy returned verdicts of unlawful killing and seven people at Townsend Thoresen were charged with gross negligence manslaughter, while the operating company, P&O European Ferries (Dover) Ltd was charged with corporate manslaughter. However, the case later collapsed.

In Dover, St Mary’s church houses a memorial and a stained glass window in tribute to those who died in the disaster, while in the village of St Margaret’s at Cliffe, there is a stained glass window dedicated to three of the crew who died, Robert Crone, Bryan Eades and Graham Evans.

The Herald of Free Enterprise vessel was salvaged, then sold off and finally scrapped in 1988.

The disaster led to design improvements to roll-on roll-off vessels, leading to the introduction of watertight ramps, bow doors indicators and a ban on undivided decks.

It was one of the worst peacetime maritime disasters involving a British ship in the 20th century.

More than 1,500 people are believed to have died in the sinking of the Titanic on 15 April 1912.

Seven years later, on 1 January 1919, at least 205 people died in the sinking of the HMY Iolaire near Stornaway, Isle of Lewis, Scotland.

On 31 January 1953, 133 people were killed when a severe storm caused the Princess Victoria vessel to sink in the North Channel between Northern Ireland and Scotland.

On 8 April 1961, MV Dara, which had been built in Glasgow, Scotland, sank in the Persian Gulf after an explosive device detonated, killing 238 people on board.

Watch: The Herald of Free Enterprise ferry disaster remembered