It was pretty common to be talking to the Royal Air Force people, as they and our customer, the Foreign Air Force (FAF), were transitioning to the US Navy way of doing things.
It was not unusual to need a later meeting and sometimes the Chief Tech would say "I have the duty tomorrow, so we'll have to do it on Wednesday." No problem - I wasn't going anywhere.
Having several years of service in the U.S. Marines, I could understand duty. I pictured the guy, rifle in hand, protecting the fort.
I was there for a year or more before I realized that "the duty" was RAF-speak for "watching the still".