While collecting a new SC7 we had dinner with Shorts Chief Designer. His account of why it looked as it did was illustrated by a series of drawings on a tissue, and started with a stripped down LWB Landrover in a box, which was the requirement of the time, with an alternate role of cargo/people carrier with STOL capability. Stabilisers, a wing, engines, a fuel tank were added, and the upward lifting rear "door" completed the design.
I accepted an invitation to ride in the RHS for a demo flight at Abu Dhabi. The aircraft was parked facing into wind at the downwind edge of the apron, The pilot (Mike ??) surprised me a little by calling for takeoff clearance while still parked with - I guess - 150m of tarmac in front of us. The clearance came, at which point he applied full power, released the brakes, and executed a STOL takeoff to about 75, feet flew round the back of the terminal and landed back on the apron, stopping, I'm sure, in about 100m or less. It was the most terrifying 3 minutes of my life. Then he did it again, but failing one engine on the way round.
Exploding TPE331 engines; up to a certain production number, TPE 331 had no overspeed protection. So when another fault, eg break-up of the bull gear wheel resulting from manufacturing defects, resulted in uncontrolled overspeed, this increased until the turbine broke up, throwing debris into and through the cabin, wing and fuel tank. The lack of a turbine containment ring didn't help, if I remember rightly. This happened twice with Gulf Air. On both occasions, superb flying by the pilot saved the aircraft and passengers. Their skills were called for; on neither occasion could the aircraft maintain height due to the drag from the dead engine and its nacelle, and on the second, which happened over the desert at night, the engine, which contained a lot of magnesium, caught fire with fuel from the ruptured tank sloshing round the cabin. The fire extinguisher was ineffective since most of the cowlings had disappeared or were flapping around. Please note; my memory gets dim, and it was all a long time ago; I would be happy to be corrected on the technical detail.
The Shorts sales team were adamant that the SC7 had a better STOL performance than the Twin Otter, and this turned out to be true. Plus there were things you could put into a SC7 that a Twin Otter couldn't touch, A LWB Landrover, for example.