Terry Barnett knew it could be his last chance to say Kaddish for the young man whose death cast a shadow over his childhood — and to honour the wish of his parents.

The 83-year-old’s mother and father took in Leonard Mokotow after he was sent to the UK by his parents Mordechai and Rose, shortly after the Brown Shirts descended on the family business on Kristallnacht in 1938.

With their livelihood destroyed, Mr and Mrs Mokotow decided to send their only son to England, and he was sent to live with a cousin in Portsmouth — Mr Barnett’s father, Harry.

“We had a large house and Leonard had his own room, as did my two sisters and myself,” Mr Barnett remembered. “He was a fine boy and although he must have been longing for his parents he was always cheerful and was loved by all.”

Leonard wanted to be an electrical engineer and Harry Barnett was able to arrange an apprenticeship with the Portsmouth Electric company.

But the outbreak of war in September made this impossible. “Leonard was considered an enemy alien but he was exempted from internment. He volunteered for the army but he was turned down. He was, however, told he could not live within 20 miles of the sea,” Mr Barnett said. “My father arranged for him to continue his apprenticeship with a large Jewish electrical firm in south London, and they promised to look after him.”

This put Leonard in London for the Blitz. On Wednesday September 11, 1940 the air raid sirens sounded over Lewisham.

“People rushed into the Albion Way shelter and a German bomber miles off target pulled a lever and released his last bomb.”

It hit the shelter, killing 50 people, including Leonard. He was just 18.

“I don’t think my dad ever got over it,” Mr Barnett said. “My family wept for days. He was meant to protect him and keep him safe.”

Worse, in 1946, after the war ended, Leonard’s parents contacted Mr Barnett’s father from Paris. They said the thing that had kept them alive during the Holocaust was knowing that their son was safe.

“We were distraught, none more than my father, it was his sacred duty of care. Somehow Mordechai and Rose had survived. To this day we are not sure how or what really happened to them,” Mr Barnett said.

“My poor dad agonised for days. How was he going to tell them their son was dead?”

Leonard’s parents “were distraught, they blamed my dad and that devastated him”. They died shortly afterwards.

Mr Barnett said: “I think they died from a broken heart. My father had a stroke from which he did not fully recover.”

It tore both families apart. Mr Barnett wanted to make the trip to say Kaddish, as it had been Leonard’s parents’ one wish.

“They asked that my father visit his grave and say Kaddish once a year. We never managed that much. I think we should have done it more…I wanted to come one last time before it is too late for me.”

Last month, he caught the train from Portsmouth to see the grave in London’s West Ham Jewish Cemetery that he had not visited for more than 50 years.

Mr Barnett took his time over the cemetery’s pebbled pathways and was visibly moved as he stood at Leonard Mokotow’s graveside, the rusted name plate unmoved since he last visited 50 years ago.

“It feels very moving to be here,” he said. “I wanted to do it and I can’t explain the feeling. I just feel so sad for the life that was lost. His story is so tragic, he should have been safe, perhaps we could have done more to protect him.”

Mr Barnett said that due to his age, he did not think he would be able to visit the grave again but he hopes others will take on the task to remember Leonard, just once a year.

“I hate to think of him there going unnoticed. His memory deserves more, he should be remembered.”