In the immediate aftermath of the Second World War, conventional wisdom amongst operators and aircraft manufacturers alike held that the flying boats still had a relevant role to play in multiple niches.

One of the company's designers, C. T. P. Lipscomb, examined the prospects for building three different sizes of flying boat; these concepts were referred to as SA.6 (small), SA.7 (medium) and SA.8 (large), respectively.

[5] One early modification was the lowing of its engines, which was changed to reduce the unduly high interference drag induced by their original position.

It shared its basic configuration with the larger Short Solent flying boat, being roughly half its size and featuring some structural advancements nonetheless.

Hinged drop panels beneath the sliding windows and an external step were present to ease the typically complex mooring process.

[4] The Sealand was powered by a pair of de Havilland Gipsy Queen 70-3 inverted inline air cooled piston engines, each capable of generating up to 340 hp.

Early on in the type's career, it was determined that, while well suited for operating from sheltered waters and possessing largely favourable seaworthiness qualities, landing upon the open sea was challenging for Sealand pilots, leading to some modifications being made to improve its performance.

[7] As early as 1949, Shorts commenced vigorous sales efforts surrounding the Sealand; according to aviation author C. H. Barnes, demonstrations of the aircraft typically made good impressions on prospective customers.

[8] A further batch of ten Sealands were built and sold to a variety of small operators, including one (G-AKLW, later SU-AHY) equipped as an "air yacht" with luxurious fittings for a private client in Egypt and given the name Nadia.

[9] A third, G-AKLW (originally bought by the wealthy Egyptian client mentioned above) is under rebuild (2008) at the Ulster Folk and Transport Museum at Cultra, Holywood, Northern Ireland.