All 'Supermarine' - the Seagull V was built for Australia, the RN got effectively the same aircraft and called it the Walrus - differences were the Seagull V had HP slots on the upper wing, and the jury strut was fixed on one and removable on 'touther. A replacement was designed, with a tractor engine - all new, but the same configuration apart from the engine, and that was the Sea Otter (wot you were thinking of!) Later still a high wing monoplane variable geometry cotra-prop tractor Griffon engine version was built (and it was as odd as it sounds) called the Seagull. That was beaten by the arrival of the helicopter.
There are four surviving Seagull V / Walruses, and one chunk of Sea Otter. There is a Walrus in the Fleet Air Arm Museum Yeovilton, another, which was under rebuild by Dick Melton to airworthy but was bought by the 'Solent Sky' museum for static, but still in store. As the website shows, there's an Australian Seagull V A2-4 / VH-ALB in the RAF Museum Hendon, subject of the website, and the RAAF Museum at Point Cook has a British Walrus on display, lovingly rebuilt from a wreck brought back for Heard Island.
Yes, I wrote a book on them.
