Peoples back gardens would not be classified as places of work, not sure what the ear defenders are about. Unless there is a serious suggestion that SEN provide ear defender for people to wear in their own homes/gardens?
SEN has been an airfield since at least 1914, according to the wikipedia page, far predating the 60s houses. It is true that there might have been a lull when they purchased their homes in the 80s/90s.