Walter Sondhelm was born in Leipzig to traditional Jewish parents. His grandparents were orthodox and active in the wider community. His parents did not observe the Sabbath but were committed Jews. His father was a Zionist. Walter attended non-Jewish schools in Germany and witnessed a change in the attitude of his school friends on the rise of Hitler. His father was eager to leave Germany and he sent Walter to a non Jewish School in Surrey. He was welcomed there and besides one other, he was the only Jewish pupil. His uncle from America paid his keep and fees since his father could not send money out. His father was forced to sell his factory in 1937 and after visiting America, Walter persuaded his parents to settle in London in 1938. Walter attended Manchester University to study textile science and went on to do a further degree. He had little contact with other refugees and Jews. He was interned during the war in three camps in Shropshire, Huyton and Sefton on the Isle of Man where he worked as an intelligence officer. The university asked for his release to do research of national importance.
He got a job with Ashton Brothers in Hyde, which later taken over by Courtaulds. He achieved a managerial position and lectured part-time at the university. He was married in 1958 to a former refugee and had three children. He married again in 1980s.