When the stern of the RMS Titanic disappeared into the icy depths of the Atlantic ocean, Alexander Littlejohn watched as he rowed a lifeboat of survivors to safety.
A century later, his grandson Philip will be following in his footsteps by sailing to the spot where the doomed liner sank.
The former school inspector, who has written books and regularly lectures about the 'unsinkable' ship, said his grandfather, who worked in the first class dining room, never talked about his experience.
"I think he felt guilty that he survived when so many went down with the ship," he said.
"It's going to be an emotional journey for me and the relatives of others who were on the ship."
The 66-year-old will be one of 1,309 passengers aboard the Titanic Memorial Cruise which will set sail on Sunday next week from Southampton retracing the passenger ship's maiden and ill-fated voyage across the North Atlantic.
Mr Littlejohn, of The Crescent in Maidenhead, will be giving a lecture and will also take part in a special ceremony held on board the cruise ship Balmoral at the time and place the Titanic went down.
It hit an iceberg at 11.40pm on April 14, 1912 and sank two hours and 40 minutes later, with the loss of 1,517 lives.
The wreck still rests on the seabed where it sank, 375 miles south east of Halifax in Canada, which Mr Littlejohn visited in 2001 in a Mir submersible, a tiny submarine that was used in the 1997 blockbuster film by James Cameron.
He added he is looking forward to seeing all the sights his grandfather would have seen, especially the statue of liberty.
"It was something my grandfather saw on numerous occasions when he worked on cruise ships," he said.
"But that night he must have thought he would never see it again. I cannot imagine how he felt when he finally reached New York."
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