Information on When and Why Pawson Culley Returned to UK

Pawson emigrated to New York in 1923, he is in the 1930 New York census with wife Mary and son's Leonard & William. He re-married in 1940 in New York but died in England in 1977, his son Leonard also died in England in 1993 I cannot find when he returned to England and would love to know when and why.