His original plan was to write the biographies of all 19 station managers, including his late father, Charles, and add several articles and photographs collected by his father and him.
But the research became ``captivating'' and the project grew, he said at the launch of his book, A Scrapbook of History - Awarua Radio ZLB, on Saturday.
``I got to the end of the managers and I had hoards of information ... from people all over the country. Eventually I knew I had the makings of a book.''
The Awarua maritime radio station ran between 1913 and 1991 and was one of four in New Zealand operated by the Post and Telegraph Department. The radio operators handled telegrams, broadcast weather reports and maintained contact with ships at sea.
During both world wars, staff played an important role internationally, eavesdropping on German and Japanese ship communications and pinpointing their locations. The station was considered so important a Home Guard camp was established there during World War 2 and guardsmen were rostered to protect the station day and night.
Mr Glennie said it was New Zealand operators who warned the Australians Japanese midget submarines were nearing Sydney Harbour in mid-1942. Three submarines entered the harbour. Two were detected by the authorities, but one attacked and sank the converted ferry HMAS Kuttabul, killing 21 sailors.
Mr Glennie's father worked at the station for 30 years until his retirement in 1976, and the family lived in one of the cottages at the station for 15 years.
Mr Glennie's book includes hundreds of photographs, newspaper clippings and reproductions of official documents as well as anecdotes and biographies.
At the launch he said compiling it had been a ``labour of love'', and thanked all those who had given him information and shared stories.
He has donated the copyright for the book and sale proceeds to the Awarua Communications Museum, which was opened at the start of this year in the former radio station building.
About 60 radio enthusiasts and other guests gathered for the book launch, including Neil Sanderson from the Musick Point Radio Group in Auckland. Musick Point was the location for Auckland's coastal radio station, which closed in 1993.
Mr Sanderson said Mr Glennie's book was important because it highlighted a little-known area of New Zealand history.
He described Mr Glennie as a ``relentless and persistent researcher'' who delighted in sharing his interesting finds with others.
Book inquiries: Mr Glennie, 03 213 0492 or 0274 478-459.