By the BBC's John McIntyre

When RMS Titanic broke in half and plunged nearly three miles into the blackness of the North Atlantic, the world was stunned.

That night - 14 April 1912 - would be indelibly scarred in the pages of history.

1,523 people lost their lives as this potent symbol of human ambition slipped into the icy seas without regard for the class divisions so prevalent on board.

Millvina Dean is the most famous survivor. She was just nine weeks old when she was bundled in a sack into lifeboat 13.

She has recently celebrated her 90th birthday and tells a remarkable story of the tragedy that has come to dominate her later years.

Millvina Dean is a legend amongst Titanic enthusiasts

It is a story which has she has gleaned in minute detail from her mother.

"My parents heard a crash and my mother said: 'Apparently the ship has struck an iceberg'."

Like a lot of the passengers though, Millvina was travelling third-class, which made it difficult to get on deck.

"It was so dreadful for my mother. It was heartbreaking.

"She said goodbye to my father and he said he'd be long later. I was put into lifeboat 13. It was a bitterly cold night and eventually we were picked up by the Carpathia."

Maritime law

Millvina, her older brother and mother were saved.

But like so many of the men, her father perished because they simply were not enough lifeboats - one of many shortcomings on Titanic which led to major changes in maritime law.

Millvina became a celebrity almost overnight when the wreck of the Titanic was discovered in 1985.

Millvina mother was able to get her and her brother to safety

There are numerous societies dedicated to the memory of Titanic. Some of their members' lives are devoted to the subject.

Millvina, who has lived in Southampton for most of her life, receives hundreds of letters each year from 'fans'.

She said: "Some people are obsessed with me. Some even look upon me as if I am the Titanic!"

One man who knows her story only too well is Philip Littlejohn, a schools inspector whose grandfather Alexander, a first class steward, was in lifeboat 13 and rowed her to safety.

He has since written a book about the night that changed so many lives and saw his grandfather's hair turn white within six months of the disaster.

He describes the death of the superliner, based on his grandfather's eyewitness account.

Alexander Littlejohn rowed lifeboat 13 to safety

"All her lights were burning brilliantly. She was a blaze of light; her stern went right up into the air.

"There were terrible cries for help, awful and heartrending. That was the last time my grandfather saw Titanic."

It is an account which Mr Littlejohn uses to bring the story of Titanic back to life when he gives talks to schoolchildren.

He was able to pay his respects to the many who died when he became the first relative of anyone aboard Titanic on the night of the disaster to see the ship lying on the seabed.

Bottom of the ocean

He joined an expedition last year to visit the site of the world's most famous wreck.

Travelling in one of two Russian Mir submersibles, he joined a leading member of the British Titanic Society, Steve Rigby, on a journey to the bottom of the ocean.

They travelled 12,500 feet (3,840 metres) down to see at first hand the haunting images of this once-mighty ship now being eaten away by the sea.

Philip Littlejohn was able to visit the Titanic wreck

"When I look at some of the pictures that I took, such as a single shoe lying on the seabed in the debris field, I feel we were intruding into a world of collective and personal grief which needs treating with the greatest respect," he said.

He is convinced the story of Titanic will continue to enthral for years to come.

"The 90th anniversary still has four living survivors and hopefully some will be there for the 100th.

"But the story, I believe, will live on long after the last survivor and the ship has gone - because the name Titanic will always be remembered as a disaster which shook the world."

Personal journey

For Mr Rigby, a postal worker, it was an intensely personal journey to the wreck site to pay tribute to those who worked on board.

"Seeing the Titanic was the biggest thrill of my life, but also one of the saddest.

"Nothing will ever compare with the excitement of descending two-and-a-half miles to the bottom of the Atlantic and seeing the Titanic.

"I got particularly emotional seeing the ship's wheel; I can't really say why but perhaps it was thinking of the vain attempts to steer the ship away from the iceberg."

The wheel of the doomed ship

He laid plaques on behalf of the victims.

As the 90th anniversary year, Titanic will be the subject of many conventions around the world, including in Southampton, from where her maiden journey began.

"There was hardly a street where someone didn't know someone who was lost," said Mr Littlejohn.

Titanic's name will forever be remembered as one of man's greatest follies.

"She was filled with some of the world's richest first class passengers down to the meekest, humblest emigrants embarking for a new life in the new world," says Steve.

"They would all be drawn together to survive or die in a tragedy that would shake the world."

Exclusive adventure

Since Titanic's demise, she has been immortalised on the silver screen; she continues to generate fortunes for people and she continues her alluring association with exclusive adventure.

More people have been into space than have visited the wreck.

Yet Millvina says she cannot understand why anyone would want to visit what is after all a maritime grave.

She said: "I only hope those who do, have respect for those who died.

"It's a tragedy that should never have happened. I look upon my father as a hero. If it hadn't been for him, we'd have gone down like so many other thirds class passengers."

Titanic was then, and is now, a classic story of heroes and villains. She remains a monument to a 20th century dream that became a nightmare.