Gumtree, his career was in Patent Law, which he entered by the then common route of getting a B.S. in Physics, going to work at the Patent Office, and getting a law degree at night. He got a Master's degree in Math at night too, but the math was mostly a hobby, and many of the math papers were written after he retired.
It was a good family for bookworms, as he loved to share his wide-ranging interests with us, and our mother, who had been a librarian, filled in the rest.