Complex sentence: During World War II Avon was occupied rebuilding aircraft and with peace tried to go back to car body making but that market had largely disappeared for good but they were kept occupied by repair work and some conversions including hearses.
Split into simpler sentences: During World War II Avon was occupied rebuilding aircraft and with peace tried to go back to car body making. That market had largely disappeared for good, but they were kept occupied by repair work and some conversions including hearses.