Supermarine Seagull (1921)
The Supermarine Seagull was a flying boat produced by the British aircraft manufacturer Supermarine. It was developed by Supermarine's chief designer R.J. Mitchell from the experimental Supermarine Seal II. Development of the Seagull started during 1920.
Source: Wikipedia — Supermarine Seagull (1921) (CC BY-SA 4.0)