William Harry Busby, from Wolverhampton, served aboard HMS Keppel in the Second World War, where he took part in daring convoys to Russia and Canada.
Harry has been awarded a handful of military medals for his bravery.
But his granddaughter Zoë Zangaro, 27, said: “I am worried time is running out to reunite him with his former shipmates.
“I believe Harry could be the last surviving crew member. His clock is ticking and it is just heartbreaking.”
The last shipmate Harry knew was a man called Ted Billingham, from Nottingham, who died several years ago. He attended his funeral.
Joe Bennett was another shipmate who has since passed away. The three of them were best friends.
Harry served as a torpedo-man aboard HMS Keppel where he prepared torpedoes and depth charges - an anti-submarine weapon - to be fired.
He lost half a finger which got caught in machinery.
Harry was just 17 when he signed up, and lied about his age in order to join.
But he wanted to avenge his dear brother, Charlie, who died nine months earlier in action, aged just 19.
Charlie served aboard HMS Keith.
Sitting in his armchair next to a fire place, Harry proudly examines his array of war medals which are pinned to his blazer.
Behind his gentle and kind manner, Harry has a remarkable story to tell.
“My brother was two years older than me and he went in the Navy,” said Harry.
“And he was there for nine months before he got killed. When the Germans started invading France, he was on a British destroyer.
“The first my parents knew about this was a telegram from the admiral’s office, which said ‘your brother got killed, and the captain of the destroyer, they were buried immediately at sea’.
“So that was that.
“Time went on as normal back home. They were calling people to the forces. I went out one day and my father said ‘where have you been?’
“I said ‘I have been up the naval offices’. He said ‘hang on, I have just lost one son, how could I lose another one? I am not happy about this, I have lost one, I don’t want to lose another one’.”
However Harry, like thousands-upon-thousands of brave men, put his country before himself, and put his life on the line.
His daughter Julie Zangaro, 57, explains it more simply.
“He wanted to go and kill everyone that killed his brother, which is natural,” she said.
“At 17, when he went in, his mom and dad wouldn’t give him permission because of his brother.
“He told them (the Royal Navy) a lie - he told them he was older than he was. He forged his papers.”
Harry was sent to training in Birmingham and Portsmouth before he was posted about HMS Keppel, a U-boat destroyer.
Aboard the destroyer, he took part in convoys across the north Atlantic Ocean, between Canada and England, and on to Russia in the Arctic Circle.
This was all the while German U-boats would lurk beneath the water.
HMP Keppel travelled in convoys of 12 ships to Canada, where it protected cargo ships - carrying ammunition - from attack.
On the trip to Russia, U-boats would travel out from bases in Norway, he recalled.
He also took part in the operations surrounding D-Day.
Although not directly involved, HMS Keppel was tasked with weakening the German U-boat capabilities ahead of the invasion.
Depth charges, which sent powerful hydraulic shocks, were laid down into the water.
Ahead of the trip, Harry said “rumours” went around the ship that they were returning to England. However, their destination was actually northern France.
“When we got to France, to us there was hundreds of boats - British boats - and we thought we are strong enough here,” he said.
“There was four different beaches across the coast. After two days, we came out of there. Other destroyers were stopped to protect what was left.
“But we came back only to find out we were going back to Russia for another convoy. That is how it went.”
He added: “It was an unwritten rule that if you did two trips (to Russia), you were on borrowed time, you shouldn’t be there.
“It was so cold, the weather was against you. If there was a lot of U-boats, you got no sleep, you had to be on the ball all the time.”
After the horrors of war, he has gone on to live a fruitful life.
Harry served as a policeman after the war. He married his wife Irene, who died in 2004, aged 87, and has three daughters, six grandchildren and also great-grandchildren.
His great grand daughters Gabriella, nine, and Luciana, eight, watched proudly as Harry took part in an assembly at their school, Long Knowle Primary School, on Monday afternoon, as part of Armistice Day.
With a poppy in his pocket, Harry added: “The fact that I lost a brother, and I thought, some people had it worse. I had some bad trips but I survived. That is the main thing.”
Military service runs in the family with Harry’s great nephew, Luke McGann, 19, joining the Grenadier Guards.
Anyone who may know former shipmates of Harry, or their families, or could help Harry’s family search for them, are asked to email email@example.com