Supermarine Southampton, Scapa and Stranraer

The Supermarine Southampton was the first flying boat designed after the First World War to enter RAF service, and was the first of a series of successful military flying boats designed by Reginald Mitchell.
The Supermarine Scapa was an improved version of the Southampton flying boat, developed after Supermarine was taken over by Vickers, and using technology developed for the Schneider races.
The Supermarine Stranraer was the last of a series of large biplane flying boats designed by Reginald Mitchell, and was essentially a larger version of the Supermarine Scapa, itself an improved version of the earlier Southampton.