Born December 7, 1926, to Albert and Jean Ellis of Montréal, Clayton was the second son to enlist in 1944. His older brother Ralph was already with the Royal Canadian Engineers.

Clayton was 18 years old when he enlisted. After basic training in Montréal in 1944, he went to the Signal School and became part of the Signal Corps until October 1945. Since war in Europe was over in May 1945 and Japan surrendered in August 1945, there was no need for Clayton to go overseas.