Illustration of a bulldog smoking a cigar on a light brown background wearing a white ribbon with red text on it and brown text
The 748 aircraft (referenced here on the ribbon) was designed and first built by Avro, a British manufacturer, in the late 1950s. It was the last aircraft Avro designed before the company merged with another producer, Hawker Siddeley. Following the merger, the aircraft was known as the HS 748. The HS 748 marked a shift away from British military aircraft development and a focus on developing for the civilian market. Though designed for civilian operators—and used by many over the past several decades—the Australian military invested in several HS 748 aircrafts which they used for a variety of training and transport uses.
The expression "Top Dog" is a common nickname for fighter pilots who excel at dog fighting: close range aerial fighter aircraft battle. In addition, seasoned air combat pilots were sometimes referred to as "bulldogs" for their toughness and tenacity. The combination of "Top Dog" and a bulldog image on this button are likely a reference to the manufacturer's history of developing military aircraft.
Air Combat Command. (2022, May 11). A Bulldog Returns Home. https://www.acc.af.mil/News/Article/3032388/a-bulldog-returns-home/
Wikipedia contributors. (2022c, September 21). Dogfight. Wikipedia. https://en.wikipedia.org/wiki/Dogfight
Wikipedia contributors. (2022b, August 23). Hawker Siddeley HS 748. Wikipedia. https://en.wikipedia.org/wiki/Hawker_Siddeley_HS_748